It is said that through meditation, Medicham heightens energy inside its body and sharpens its sixth sense. This Pokémon hides its presence by merging itself with fields and mountains.
– Pokémon Omega Ruby Pokédex
Mega Medicham keeps its Fighting/Psychic typing after mega evolving. It also keeps its ability of Pure Power, which doubles its Attack stat.
Stat-wise, it gains a bit in every stat, but most notably, its Attack is increased by 40, to reach 100. With its Pure Power ability, it’s equivalent of 200 base Attack, which makes it quite the heavy hitter.