I think there are some suggestions I can offer, but first I wanted to check with one of the comments that you have made.
You say that characters with a d6 in shooting can't hit. This seems a little off because the odds for hitting a TN of 4, i.e. a target at short range with no cover, are 75% for a Wild Card. I certainly have players in my games with d4s and d6s in shooting that have no problems with hitting, especially once you take into consideration how frequently a d4 will explode (1 in 4 chance).
Assuming that you are applying the rules properly, I can suggest a few things that will improve the situation:
Melee Combat
Ganging Up - This gives +1 to hit for every ally in combat with your foe up to +4. Even if a character isn't hitting they can assist with giving bonuses to other people.
Push Manoeuvre - This relies on the Strength Attribute rather than Fighting Skill, and allows you to move the target around, cause damage if you have a shield, or knock the target prone.
Wild Attacks - These give +2 to hit and +2 damage, and are extremely effective. Watch out for the reduced Parry you get though.
Smarts/Agility Tricks - These have a similar effect to Taunt and Intimidate, but are more dependent on good teamwork as the -2 Parry on a simple success only lasts until the affected creature's next turn.
I'd try and be as flexible as possible as GM when players come up with ideas for tricks. One of the best examples I've ever had is with someone who grabbed a can of baked beans and threw it whilst shouting 'grenade!' - as a successful smarts trick it had all of the enemy diving for cover
Ranged Combat
Aiming - Do nothing for a round whilst you aim and you get +2 to hit, which is very effective.
Using a shotgun (depending on the setting) - gives +2 to all shooting rolls if you fire a single barrel. Makes you more likely to hit an innocent bystander though.
You've also got double tap (+1 to hit and damage), and three round burst (+2 to hit and damage) with certain weapons.
Other general comments
There are a few general Edges that can assist with low skill combat characters. One that springs to mind is Elan, which gives +2 to any roll you make as a result of spending a Bennie.
Consider giving non-combat characters things to do whilst others are fighting. Dramatic tasks are good for this, but get a bit old if overused. For example, your computer hacker is trying to break into a security system so you can escape the room you're in whilst the rest of the group are holding back the drug enhanced super mutants.
Also don't forget that a successful trick, taunt or intimidate with a raise will shake your opponent, making them MUCH easier to wound. For high toughness creatures this becomes a hugely valuable tactic.
Also, there are a couple of general resources that you might find useful:
Savage Worlds Combat Survival Guide - which summarises the options you have, along with suggestions as to when each of these might be used. It should be noted though that there are a couple of new options introduced in the Deluxe version of the rules, e.g. pushes, that are not covered on this sheet.
Whispers From the Pit - Expanded Trickery - which goes into details about tricks and how to run them as GM. ... looks like this site has been corrupted
The core rules don't say how big or small a group can or should be. Indeed, it's not really an important concept compared to other roleplaying games, such as Dungeons & Dragons (where it's strongly recommended that you have the "core four" types at least).
I've run many Savage Worlds sessions for as few as two players (both one shots and multi-session campaigns) and it generally works out. Pinnacle mentioned a while back that they are even working on a solo Savage Worlds adventure, so I imagine it could even work in a one GM/one player game.
Going a bit beyond the scope of the question, I think that there are things that need to be run a little bit differently with a small group than you would with a 4-6 player game:
- Combat needs to be a bit smaller and/or more rare. Especially since in Savage Worlds characters can be killed by a single bullet, it's important that the characters aren't going to have half their firepower eliminated with a lucky die roll. If something goes wrong, there is only one character around to pick up the slack. Many adventures from Pinnacle already scale for this by saying things like "two enemies per player" for setting up combat.
- Characters probably ought to be more well-rounded, since you don't have enough characters to fill all the specialized roles.
- Allies are an excellent way to help in combat and fill in any skill gaps. The core rules explicitly state that they ought to be controlled by the players and, especially if they are Extras, I find that they generally are simple enough that anyone familiar with Savage Worlds can play them along with their own character. For small games I usually give at least one out.
- If your players enjoy roleplaying, consider relying more on that than the mechanical rolls since that is oftentimes enhanced when you have more time to put each player in the spotlight
So in short, it totally does work with only a few players. You might need to tweak the scenario a bit along with the number of enemies, but there is nothing mechanically preventing it from being run with only a few players.
Best Answer
Well, as you stated, a smart approach when this happens is to just ask the player, but with that out of the question here are some options I might use in this situation:
Give objectives. Try to add in something extra to the fight, maybe a lever to pulled, or even better, a door to be unlocked (either locky-picky, or with hacking). A cool way to use this is to have a battle that the group (including him) isn't ready to face, but giving them an "out". Just make sure that they know that they can't win this fight — nothing is worst than hubris getting in the way of an awesome escape scene. With this the rest of the group still has stuff to do (the hacker can try and open the door while someone strong might try to barricade them a bit, etc.) while he is getting challenged to "real" fight.
Boss with minions. This is less fun in the long run, but here and there it could do you wonders — have a fight that centers around a main baddy. This leads to one of two options: a) That he has to focus all of his efforts on the baddy, giving them time to fight the goons; or the somewhat better b) of letting them take on the baddy (merely being strong isn't enough, it needs some skill or combination of skills to kill him) letting them show off what they are good at, and giving him the feeling of power that comes with mowing down 7 baddies in 2 rounds.
Split the party either before the fight, or through the sheer size of it (he can't be everywhere at once, can he?), so that he might take out everyone in one room, but that doesn't quite cover the next room where the other part of the group is fighting.
And yes, having less combat, even in Savage Worlds, is a good thing — it helps you evolve as a GM, and it's often more fun than "another random fight". Fights are cool, but they aren't the only cool thing, not in role-playing games: the coolest thing, is playing a role.