I always pick Charmander.
In the original Red/Blue, slash was broken and crit 100% of the time so when charmeleon learns it, rest of the game is easy. Plus you could easily beat the game using only your starter.
You can beat red/blue with a rattata its not exactly challenging by any stretch of the imagination.
I was referring to having one irl as a larp. Would you want a fire lizard a turtle that shoots water or grass turtle with vines that can whip things?