What I thought about this episode is that before Bulbasaur would launch Solarbeam Attack on Team Rocket, Ash was embarrassed that it was being made fun of. But it would've been off evolving into Ivysaur so it can get strong, but what will it happen if it did repeat the same things that Charmeleon did to Ash? It will make his life hard, so it stayed the same probably because of that in my opinion. This reminds me that Pikachu refused to evolve in "Electric Shock Showdown".
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