The best three in my opinion are torchic, chimchar, and totodile. Torchic gets speed boost in which(with a proper nature ex. adamant ,jolly) then you got yourself a nice physical sweeper. Chimchar is the same story but it's more viable as a mixed attacker and an overall better movepool. Totodile is good because of it gets sheer force. Combined with crunch and ice fang, and it's gonna be awesome. I have 3 files, all of which use the fore mentioned pokemon. All of which served me well.
Keep in mind that you'll get mudkip, bulbasaur, and tepig later, so don't choose them.