Sumo Wrestling
Defaults: None.
This unarmed combat skill represents any training at grabbing, shoving, and tripping – not just the traditional Japanese sport of sumo. Roll against the higher of DX or Sumo Wrestling to hit with a grapple, slam, or shove, or to make or resist a takedown. If you know this skill at DX+1 level, add +1 to ST whenever you make or resist a grapple or takedown, and whenever you attempt to break free, and +1 per die to your damage when you slam or shove. These bonuses increase to +2 if you know Sumo at DX+2 or better.
When you defend with bare hands, Sumo Wrestling allows you to parry once per turn. You must use both hands. Your Parry score is (skill/2) + 3, rounded down. This parry is meant to ward off slams, grapples, and bare-handed slaps. You parry at -2 vs. kicks and -3 vs. weapons. For complete rules for parrying barehanded, see Parrying Unarmed.
Martial Arts
This skill is named after a traditional Japanese form of ritual combat (see Sumo) but could be part of any style that alternates shoves, slams, and sweeps to unbalance the enemy. In the real world, this combination is uncommon but not unknown – see T'ai Chi Chuan. Sumo Wrestling also suits practitioners of synthetic "strong man"” styles (sumotori have competed at no-holds-barred fighting, and other contenders have no doubt adopted their best techniques), rugby players-turned-action heroes, and super-strong comic-book characters.
The ST and damage bonuses from Sumo Wrestling only apply when using the skill. They don't "stack" with Brawling or Wrestling bonuses in situations where more than one skill could apply.