let me ask you this, when your charmander evolves, did you suddenly lose your starter pokemon?
Let me ask you this, when there is 22 options total and charmander still wins, is he the best or does nostalgia rule all?
Define best, though. Game function? Probably not. However, things like character design are more subjective and, while Charmander and his evos have simple designs, it's hard to deny that they're pretty appealing. He'd definitely be in my top 10, if not my top5.
Four of my top five are easy (because I exclude Pikachu, otherwise 5/5 would be easy): Bulbaur, Torchic (granted, more for the evos), Rowlet, and Mudkip.
Best: Adjective The one who is better than the rest of them