I am curious how ash got him
A mean trainer left charmander ( that's when ash met it) the trainer Damien saw no hope in it because it was weaker than the rest of his Pokemon. He tricked charmander into thinking he would come back for it but never came. Day after day it waited on the same rock Damien left it on. One stormy night the gang ash misty and Brock went out to get it. The next morning charmander went back to the rock. When Damien saw that charmander learned flamethrower he made up a story about how he was sorry. It didn't believe his lie and decided to join ash on his journey.
I hope this helped!
Well, Ash found him as a Charmander, which Damien left because it was too weak. Ash then took care of him, and then raised the Charmander to be a Charizard.