Well, i really do not think that mewtwo is the best, but i agree with Mrayquaza because it IS the only pokemon that can mega evolve without a stone... along with really good moves and type, i totally agree. Also, this is not pokemon card-wise.
So, lets have a discussion on what pokemon is the best competitively! You can include any pokemon that does not suck and have a reasoning for that pokemon being there. Comment your answers!!