Aizen vs Master Roshi

Random encounter.

No knowledge of each other.

Takes place in Roshi's school.

gotta hand it to Aizen because of his shikai. I forgot how fast Roshi is though so there's a chance that Roshi could maybe blitz him at first before he can use his hypnosis.

Roshi could vape Aizen in a single blast.

Though, to be honest, depending on which Aizen it is, Roshi might not be fast enough.