Questions about Charizard

Hi, I'm new to the game (1 week, lvl 34) and I have a question: I have the starter Charmander (it's now a Charmeleon) with 10.6k power, and I captured a Charmander with timid nature (1.6 power). Should I continue training my starter Charmeleon or should I leave it and train the new timid Charmander? Also, how do you recommend me to train that one? (I don't know what training methods there are in this game). Thanks.