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I still think BW started out well and had potential to be the best series of Pokémon. While Ash's rival was bland Iris and Cilan had rivals with a lot more personality and there were tournaments where each of these characters would battle opponents they normally wouldn't. Team Rocket had a storyline that was going somewhere and weren't just appearing every episode just for the sake of it. And Ash was catching more Pokémon meaning he would mix up his team more often, the potential was there for a league with multiple 6 on 6 matches where Ash's team was different each time.
Then they ruined all of that. The rivals were ditched, what should have been the biggest tournament was rushed to get to another story arc they also rushed, the episode Team Rocket's story was building up to was banned and without something to build up to this take on them was boring, Ash catching/using more Pokémon had a side effect of the team feeling weak and Ash only had one 6 on 6 league match (against an opponent with only 5 Pokémon).