i think a torchic. even though its weak at the beginning...(well.. not really.. just small...) it evolves into blaziken.. which is REALLY strong!
Yea torchic is good, especially against the first gym if you train it to level 16 and evolve it it learns Double Kick.
On my opinion,i think pikachu because it's a basic pokemon.
Ya I would go with Pikiachu to. Just cause I like him.