Mega Garchomp would get a Speed boost and a slight Attack boost. Idk about the ability, and maybe the type can change to Dragon/Water with the whole shark thing... Or not... Dragon/Ground is still great.
When equipped with the Champion Gloves, Hitmonchan becomes Mega Hitmonchan!
His new, unique ability is Rocket Fist, which gives all punching moves +1 priority. Bullet Punch and Mach Punch, which already have boosted priority, are elevated to +2 priority. Mega Hitmonchan also gets a boost to his Attack stat and his Defense stat!