There is no fundamental guide on "numbers of powers" as that doesn't exist on this level of abstraction. However, there are ways to quantify most of what a controller/leader does and apply it to the concept of party-as-character for purposes of optimization.
Let us start with the most difficult to classify, controllers. (And some theory)
While the other classes have axes the paper by myself and Russell: Damage Dealing (strikers), Damage Capacity (defenders), and Damage Mitigation (leaders), controllers have no epistemological representation as an axis because they do so many different things.
First, let us set aside the measurements of controllers that are adequately represented by other axes:
Damage Dealing can and does effectively eat their AoEs. It is possible to apply a multi-target multiplier as presented by me here. The math presented in that chart was derived from a Monte Carlo simulation that I believe has significant validity. Therefore, it is possible to build a "blaster" controller with reference to the striker damage chart. The trick is that the controller, by virtue of her multi-targeting, attacks the encounter as a whole. While this oft-times does more damage, the controller qua blaster is much less effective than a striker in "damage mitigation" by virtue of not applying that all-important status effect: dead.
Debuffs are quite adequately represented in damage mitigation or damage dealing.
If a controller applies penalties to a monster's defenses (causes it to grant CA, or equivalent thereof), that can be captured as damage dealing: you multiply the bonus in accuracy by the damage output of the other members of the party who would normally take advantage of your buff. If you apply increased damage, you multiply the normal accuracy of others attacks by only the increased damage (multiplied by your accuracy, of course).
Debuffs to the monster's accuracy or damage output are under damage mitigation.
The most common: dazed, is a pain to model. Most of the time, you're not going to be mitigating all that much damage from dazed. (Limiting tactical options yes, damage no.) Given that monsters can charge or do ranged attacks. You are, however, allowed to count it as mitigation if it accompanies forced movement, proning, or another character using the dazed to have the monster do less damage.
Still, debuffs are nominally damage mitigation.
Buffs should be treated as reversed debuffs (who'da thunk?). Benefits to PC accuracy are multiplied as above, And benefits to PC defenses are as above.
Sliding and forced movement is a right pain. As an off-the-cuff rule of thumb, slides of 1-2 should effectively be considered combat advantage, and 3+ for an extra target in another player's AoEs. Beyond this, I don't have any adequate models of the specific impact that a slide has as the slide resides almost purely in the mechanical-functional level of tactical expression on the battlefield.
With the edge cases out of the way, we can now look at the Damage Capacity and Damage Mitigation axes. Consider sections 2.2.2 and 2.2.3 of my paper.
Damage Capacity notes:
"A functional categorization of this axis articulates four benchmarks:
4 rounds, 8 rounds, 12 rounds, and 16 rounds. The nature of the system
makes it difficult to make a character able to survive less than four
rounds of combat (on average), and exceedingly few combats last more
than 12 rounds, much less 16. The higher numbers on this axis
represent a willingness to engage multiple enemies at the same time,
rather than a willingness to literally stand in front of an enemy and
ignore them for 16 combat rounds."
Thus, you can measure how your powers, through damage mitigation, impact other players' damage capacity. Defenders have it easy, of course. I would recommend a defender be a 12 round character and most others shoot for 8.
Damage Mitigation, as ever, is the annoying part, as it is a measure of how you influence other peoples damage capacity and damage dealing axes. As a theoretical axis its fine, but it is indeed difficult to quantify.
The best way to quantify it (not expressed in my paper due to length limitations) is if everyone in your party is using this model. Then you can measure the amount of change your powers create in the other two axes.
No change, obviously, would be the zero-point of the axis. And a lazy-lord would be the maximum, as they take no standard actions for themselves, but always use their powers to influence the other players' characters.
Functionally, however, there are no recommended "quantities" of actual buffs as they do not exist on the same mechanical-theoretical level as these axes. The buffs and debuffs are how one expresses these axes on the mechanical-functional level. Therefore, favourite no specific buffs when considering them on the mechanical-theoretical, but instead consider how they impact the party's damage capacity and damage dealing.
It is therefore possible to consider controllers and leaders in the damage-capacity and damage dealing axes if one considers the party as a single organism. If you calculate the everyone's damage-dealing capabilities, you should be able to observe the difference between that and the expected number of monsters who die to the party's hand per round. If there's a difference and you're a controller/leader, inspect your powers to see if they can make up the slack through the measurement techniques above.
You can perform a similar operation on damage capacity.
"How can I build my character to take advantage of charisma as much as possible?"
Short answer: you cannot further build your character mechanically (except for one Edge from Slipstream). By design, Charisma is of limited, non-combat use, but where it is used it is very powerful.
Long answer: to get to +10 Charisma, you've already maxed out all of the Charisma Edges and taken a Race with a Charisma bonus (the Valkyria race from Slipstream combined with the Attractive, Very Attractive, Charismatic, and Noble Edges from the core). You've already super-specialized your character in that direction (spending several Advances to do so) and there are no more Edges that can boost it.
Charisma is intentionally limited in that it only works for two trait rolls: Persuasion and Streetwise (and a successful Persuasion roll raises the result on the NPC reaction table; two with a raise, but it's capped at that). These are both non-combat rolls. What this means is that you are really, really good at convincing people of things and chatting around to find out information and that general people will always be Neutral or better (the GM can still of course ignore the NPC reaction table and just have someone be hostile. You still have enemies). But aside from boosting your Persuasion and Streetwise, you've more or less maxed out your ability mechanically. You are essentially a well-liked superstar who can get their way whenever they want.
Realize though that there are limits to a high Charisma. Although you can probably talk a great deal on price or get someone to reveal information that isn't common knowledge, having a high Charisma does not equal mind control. No matter how well you persuade someone, they won't let you into a classified building if it means they'll lose their job. More importantly if someone wants to kill you, you might be able to convince them to stop if they are unsure of it, but not if they're hell-bent on killing you, no matter how charming you are. And that's the major limitation: being attractive and charismatic is helpful in social situations, but doesn't matter if someone is trying to kill you. Again, this is by design (and it's how it works in real life).
There is one Edge from Slipstream that you can take that would help fill in your combat weakness. The Femme Fatale/Ladykiller Edge lets you use Persuasion (modified by Charisma as usual) as a Test of Wills during combat. Like other Tests of Wills, this will allow a +2 to your next action against them and possibly Shake them (but not wound). This will help you set up for an attack or aid your teammates, but it won't completely get them to stop. There isn't anything in High Space that modifies Charisma, Persuasion, or Streetwise.
So to sum it up, you're at the end of the line with your high Charisma character. Except for the Femme Fatale/Ladykiller Edge, there is nothing more you can do to build your character, so you will need to get creative and find story reasons for how such a high Charisma can be helpful. Also, it's time to diversify and fill in the weaknesses you've left by spending so many Edges on boosting Charisma.
Finally, I'd recommend talking with your GM about your character. If you were running that character in my game, I'd have a hard time challenging you with a +10 Charisma because you'll blow through most every social situation I try to throw at you and honestly I'd be concerned about that making the game not fun (after all, what's the point of running them?). Savage Worlds isn't really a min-maxing game like D&D and I'd instead suggest that, for the fun of the game, you retrain some of your Charisma-boosting Edges into something else so that I can still make social situations a challenge you.
Or if you insisted on keeping it, I'd make your high Charisma a curse. Like give you an annoying fan who always follows you around, even in combat. Or make it so that people stop you to get your autograph when you are trying to get away. Or have the tabloids telling all sorts of stories about stuff you supposedly did. Just saying, in the hands of a vindictive GM, high Charisma is a curse!
Best Answer
Short Answer
Increase your Fighting and Vigor, get Arcane Background (Chi Mastery) and deflection, use a spear (Str+d6, Parry +1, Reach 1) for a weapon, and use good tactics. Also, double-check that you are using the correct rules for ranged weapons at melee range.
Long Answer
Let's review what a tank is
According to Wikipedia:
So the parts that make up a tank are:
You've added an additional criteria: "able to Shake", which we will assume means able to do enough damage to affect a fight, but not expected to do a significant amount
Redirect attacks towards yourself
There is no way in core Savage Worlds or Deadlands Reloaded to force an opponent to attack you instead of an ally, and that's by design.
The best way to fill this role is to be the most immediate threat. You've got the right idea that you should be a melee fighter in this case, especially in a gun-heavy setting like Deadlands for a number of reasons:
I'm a little surprised that you said you were having trouble if enemies had guns, so I think you should double-check to make sure you are following those rules correctly.
The main downside to attacking in melee is that enemies can get a Ganging Up bonus against you. However, the Deadlands Reloaded Martial Arts Edge makes you immune to that, so you're right to take that. This is a really broken effect that has not appeared in any future settings, and I am absolutely certain it will be removed in a future version of Deadlands Reloaded.
Recommendations:
Survive multiple attacks via one or more of the following
Armor (i.e. Toughness)
Armor as such doesn't really exist in the Deadlands setting because all pistols have Armor Piercing 1, and all rifles have Armor Piercing 2. Sure, you could have the equivalent of plate mail by strapping cast iron to your chest, as in Back to the Future Part III, but for all intent and purposes, there is no armor in Deadlands.
However, Savage Worlds does have Toughness, which makes you shrug off or otherwise not be affected by damage. You'll want a high Vigor for that, both for soak rolls and a high Toughness.
There are a couple of other ways to improve Soak rolls and increase Toughness:
There is also Brawny, which grants +1 Toughness, but it's almost always better to just increase your Vigor if you are able to, since you get +1 Toughness anyway as well as better Soak rolls.
Let's not forget getting out of Shaken as well. Assuming you are using the revised Shaken rules from May 2015, you shouldn't have too much trouble getting out of Shaken with a decent Spirit. If you are having trouble, the Combat Reflexes Edge helps a lot.
You mentioned "a Shaman with bear stance" as a possible character option, presumably for the increased Toughness. I'm going to guess you mean the shape change power, but changing into a bear is only available to Heroic characters, so that is not available to a Novice character.
Receiving healing
There isn't really anything that an individual character can do to help with this. Having someone in your party who can cast magical healing can help a great deal (non-magical healing via the Healing skill takes 10 minutes, so is too slow for combat).
Evasiveness
There are two types of evasiveness: melee and ranged. Melee evasiveness is tied to Parry, which is increased by Fighting. Fortunately, Fighting is a skill that you'll already have a lot of as a melee fighter. Boost that as high as you can. This will also help against ranged combat in close quarters, since enemies shooting pistols at you point blank have to go against your Parry, instead of the usual target number of 4.
If you frequently fight in open areas, consider the Dodge Edge, which gives –1 penalty against ranged attacks. If you fight in closed quarters or areas with lots of cover, skip this and use better tactics by taking cover, crouching, taking advantage of dim light, etc. (See How do I improve my ranged defense in Savage Worlds for more information on how to improve ranged defense, especially through tactics).
The best way to get better at evasiveness is through the deflection power, which provides a –2 penalty to both melee and ranged attackers trying to hit you (–4 with a raise). I'm baffled that you said this was something you tried that didn't work for you, as this is an incredible way to avoid taking damage. At my table, I frequently have trouble hitting players who have this up.
Also, don't forget that martial artists get an extra benefit with deflection:
Self-regeneration
Casting the healing power on yourself would cover this, but to be honest, it's better if you can get someone else to do this for you.
There is the Knack (Breech Birth) Edge in Deadlands Reloaded, which allows you to spend a Benny to automatically heal one wound without a roll. If you find yourself soaking one wound, this may be an option for you.
Recommendations:
Deal enough damage in a fight
We've already talked about increasing your Fighting, which helps your Parry (thus increasing your melee defense). Consider using tactics like Wild Attack and Gang Up bonus to improve your chance to hit.
I'd recommend not going bare-fisted with a martial artist. Instead, use a Spear (Str+d6, Parry +1, Reach 1, requires 2 hands)* This has two advantages: you become a threat to your enemies from one square away, and you increase your Parry even further, increasing your melee defense. I think of the two, the Parry +1 is more valuable than the Reach 1 because ranged enemies can shoot you at a TN 4 from one square away, but against your Parry adjacent. However, Reach is good against melee enemies, since they tend not to have it.
Honestly, I don't think that Edges like Superior Kung-fu: Wing Chun are worth it for your goal of being a tank, although it may be useful if you decide you want to attack more in the future.
* There are also more niche weapons, like the Sai (Str+d4, +1 Parry, +1 to Disarm), in Deadlands Reloaded: The Flood Player's Guide.
Miscellaneous
Arcane Background (Chi Mastery) gives you two powers. I've already strongly recommended deflection. As a second power, I recommend boost/lower trait, since that is a pretty versatile power. You can increase your Fighting or Vigor, or decrease your opponent's Fighting, Vigor, or Shooting.
Your GM is giving you a really tough time if Parry and Toughness 6 is "trash" for Novice characters. A Veteran Gunman has Parry 5 and Toughness 6, and they're supposed to be tougher. Is there any chance that you're expected to run?
As for the "boss", the Taxidermist has no obvious weaknesses. I recommend following the combat tactics on Pinnacle's Combat Survival Guide. He's got a high Parry, so your ranged allies staying out of melee and firing their guns is the easiest way to hit him. If they do a called shot, they should be able to do decent damage. In this particular case, the Taxidermist is stronger than you as a melee fighter, so I think your job is to just keep him busy and not worry about damaging him, just setting things up so that your ranged allies can shoot him. When fighting gunslingers, it will be your time to deal lots of damage.
Putting it all together
Putting this all together, I think that a Novice Deadlands Reloaded character would be optimized as a tank with the following build:
In melee combat and adjacent ranged combat, the enemy must roll an 8 or higher on their attack roll in order deal any damage. If deflection is up, they have to roll a 10 or a 12, depending on if they succeeded with a Raise. And in ranged combat, enemies need to roll a 6 or an 8 in order to hit if deflection is up. Even if they do manage to hit, they have to roll at least 7 damage to Shake, and there is a good chance they will soak any damage.
In addition, the character rolls Fighting d10 to attack with his spear, possibly from one square away, and will deal 2d6 damage. They also have the boost/lower trait power
The main flaw with this build is that they are extremely susceptible to Agility and Smarts Tricks, since they have a d4. A clever GM will exploit those. It may be good to put a d6 in those instead of pushing Toughness. Also, there are no social skills or other useful things, which may mean your character will be crippled in social situations or other non-combat encounters. A lot of skill points were spent by pushing Fighting above Agility, so a higher Agility means more skill points for other purposes.
The rest comes down to using tactics. And making sure you are following the correct rules for ranged weapons in melee combat.