Aizen's strength grows so much that he can damage almost anything. Aizen's new-found power boosts his speed to the point where even captain-level opponents can't register his movements. Regeneration: Aizen also shows signs of regeneration.
Aizen is in his "chrysalis" stage after his first transformation by the Hgyoku, with increased spiritual power, strength, durability, and speed. After completing his "chrysalis" stage, Aizen became even more difficult to harm, destroying the Ktotsu simply by colliding with it, and possessed even greater spiritual power, capable of destroying souls simply by being in their presence. Aizen's strength increased in his third form, and he could teleport by breaking into shards and reforming elsewhere. He has a much more Hollow-like appearance after transforming for the final time, and he can fire powerful energy spheres from the skulls on his wings, as well as surround his opponent with an energy ring to destroy them. Quotes
Arruruerie, Aaroniero Number of Espadas: 9... Zangetsu, are you a Yhwach? Nimaiya claims that the entity he believes to be Zangetsu is actually a form of Yhwach, and that his true zanpakuto is White Ichigo, the inner hollow within him. However, the hero realizes that they are both equal parts of his personality and history, and accepts them both.
Even before his first transformation, base Aizen was comparable to base Yamamoto because he could take a Hado 96 directly with minimal dmg. Aizen, while slightly weaker than Yamamoto in general, still had reaitsu comparable to him, which is why he could hypnotize everyone in the Seireitei.
Beyond Shinigami, only three other characters can compete with Butterfly Aizen: Yhwach, Ichigo, and Soul King.
