Suggested by Sonic Aizen is known as one of the strongest Bleach characters and for good reason. He has illusions which can trick any character and then he also has enough physical skill to come to blows with multiple captains at once. In his evolved form he transcends any Pokémon final form and that spells the end for Ash. Aizen wins.
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I’ll take the tick in Ichigo’s side over Ash any day. I’ve only heard of Bleach, but I know that Aizen on his worst day could take over most of the Pokémon Trainers.
Agreed, Aizen is just on a completely different level from Ash. His Pokemon probably aren’t even fast enough to hit Aizen