This is official Ken Sugimori artwork of Mega Pikachu. Its speed goes through the roof, having the fastest speed of any Pokemon in the game, but all of its other stats remain the same. It has the ability "Oblivious" as well.

It also gains a new attack: Extreme Zap, which not only inflicts 30 damage to all Pokemon on your opponent's side, but also infatuates all opposite gendered Pokemon.