Charmander

Leveling
Flame Tail - The only reason you’d be using Charmander is to evolve it into Charizard, so Flame Tail is your best bet.

Runner
Because of Charmander’s Smokescreen move, which is a 1* purple attack that inflicts Wait on your battle opponent, and a decent 40 damage white attack, Charmander could be an OK Runner if you have just started the game, or if you are trying to create the ultimate Charizard. Unfortunately, because of Scratch, a 10 damage white attack with 32 base size, Charmander is very unreliable, and should generally be avoided.