No, there is no super special form after you hit LV 40, HOWEVER if you're not into those soft, squishy types and prefer the more muscular guts, try giving your Sumo Wrestler some muscle toner. It comes in both regular and cosmetic. The regular version will add some big boosts to Belly Strength and Weight, making it harder to deal damage to them. ...HOWEVER, critical hits deal MASSIVE damage. Harder to hit than the regular sumos, but when they DO get hit, they get hit HARD. The cosmetic version can give you the cool muscle-gut WITHOUT the buffs and debuffs.

Every species has a champion, and the champion of the pigs is the Red Butcher. No, he's not covered in blood: it's paint made to look like blood, but he's as rutheless as the paint suggests. He's at max level and rarely misses an attack. He will be a true test of your sumo-mettle.