dnd-5egrapplesimulation
Both races have the same limits on their strength, and athletics, but it's hard to imagine why. A Goliath could feasibly lift and throw a gnome, yet the Gnome, following rules as written, can pin down a Goliath, fairly easily, if statted correctly.
Is there an in-universe explanation as to why such dramatically different sized creatures can wrestle on an even playing field?
How might a DM explain a scenario in which a gnome beats a goliath in any kind of test of strength?
There is no concept of grappling in 4e.
The concept is replaced with the grab action which inflicts the grabbed condition. Which is defined thusly:
- The creature is immobilized.
- Maintaining this condition on the creature occupies whatever appendage, object, or effect the grabber used to initiate the grab.
- This condition ends immediately on the creature if the grabber is subjected to an effect that prevents it from taking actions, or if the creature ends up outside the range of the grabbing power or effect.
Breaking a grab is accomplished by spending a move action to attempt to escape, being pushed pulled or slid out of reach or by teleporting out of the grab. Escape attempts vs monsters are either set by a DC (can be different depending on whether athletics or acrobatics are used to escape), or by the monster's defenses (Fortitude for Athletics, Reflex for Acrobatics). When a PC grabs there is no DC and the character's defenses are used.
To update this to actually answer the question as now posed:
The basic action to grab someone is a standard action in which you make a strength attack against your enemy's Reflex. You are required to have a freehand, and your enemy cannot be more than one size larger than you. If you hit then you are grabbing your enemy. You may sustain this action with a minor and it may be sustained until it is escaped, you choose to release it as a free action, or you are rendered incapable of taking opportunity actions (dazed, stunned, unconscious, surprised, etc) Or you move away from the creature you are grabbing.
There are a few more rules related to the grabbed condition, but this is most of the stuff you need for play.
Monster Manual p273:
Horses have a grappling score, there aren't any special requirements excluding them from being able to grapple, and there's nothing saying horses can only react to grappling. The grapple rules, even employed literally, require a grappler to grab and then be capable of holding their opponent - the horse can do this (beginning with its mouth), so it passes.
All in all, a horse may grapple, because there is nothing mechanically preventing them from doing so.
Furthermore, the first paragraph of the Grapple entry in the 3.5e PHB:
GRAPPLE
Grappling means wrestling and struggling hand-to-hand. It’s tricky to perform, but sometimes you want to pin foes instead of killing them, and sometimes you have no choice in the matter. For monsters, grappling can mean trapping you in a toothy maw (the purple worm’s favorite tactic) or holding you down so it can claw you to pieces (the dire lion’s trick).
Holding you down purely with body weight is a perfectly legitimate grappling tactic. As @BESW mentioned, a horse can stand on you, and from there, instead of clawing you, it can stomp on you.
Best Answer
I'd like to take a different approach to answering this question: Numbers!
Presumably, this is to allow the role play opportunity of playing a Gnomish fighter who is excellent with a sword. Key stats are key stats, and cherry picking limits actively disincentivises creative character generation. No, it's probably not realistic.
Let's prove it.
Average characters have average stats: 10 across the board. Goliaths get a racial +2 to strength, giving an average Goliath a strength of 12. They also all have the racial trait Powerful Build, making them count as Large for the purposes of moving stuff.
The section Lifting and Carrying on PHB 176 says the carrying capacity of a str 12 character is 180 pounds, and the push/drag/lift weight is 360. However, that's doubled for Large creatures. Thus an average Goliath can carry around all day 360 pounds, and in a pinch lift 720.
The average Gnome weighs 40 pounds. A Goliath would need an impossible -1 base strength plus the +2 racial mod to have a strength low enough to not be able to carry around a typical gnome all day.
It doesn't say anything about throwing, but I think we're in safe territory here.
Here, I take 'statted correctly' to mean a strength of 20. You can also get higher with the better Belts of Giant Strength, or by being a barbarian, but I'll stick with the 20.
Sure. A 'statted correctly' Gnome can feasibly lift and throw a Goliath.
From the same sources as our Gnome lifting above, a str 20 character (of any small or medium race) can freely carry around 300 pounds without breaking a sweat, and can push/drag/lift a whopping 600 pounds.
Goliaths weigh 280 to 340 pounds. Thus, a feasible grappling tactic for our diminutive grappler is what you might do with a child: pick him up. A somewhat lighter than average Goliath could be carried around all day, in case of emergencies.
Actually throwing the Goliath would be a DM judgement call. If you expand your range of opponents to other humanoids, you should have no trouble tossing around the heaviest humans (weight varies), elves (slender), half-orcs (bulky), tieflings (as humans), or even dragon born (250 pounds). However, it's essential to remember that even at only 150 pounds, nobody tosses a dwarf.
The Goliaths in question are average and run of the mill. Any gnome with a 20 strength is at least in the second tier (levels 5-10, PHB 15) and thus capable (with a few friends) of handling problems that threaten cities and kingdoms. Thus, such a Gnome is a pretty famous hero and a specimen as rare as any other character with a 20 in one stat.