>It's Ash's fault that he lost the indigo league because he didn't try to train Charizard.

How exactly was he even supposed to do that? In the games, you do it by winning all the badges. Ash already had 8 of them.
>He didn't even earn half of them
Okay, it's not like he asked for pity badges. I'm pretty sure he initially turned them down but the gym leaders insisted on it.
>He should have proven himself as a worthy trainer
By this point, he beat Blaine's powerful Magmar during the one time charizard decided to listen to him, and managed to make it to the top 16 of the pokemon league. He's certainly not an abysmal trainer going by results alone.
>He should sorted out Charizard sooner.
It's a 7 foot tall fire breathing dragon. There is only so much a 10 year old can do about that.