I'd really like to see

The 3rd (Naruto) VS. The Captian Commander (i don't remember his name) (Bleach)

They are both badass old guys, both can use fire-type techniques, both strongest in the village in their prime.

Kabuto (Naruto) VS. The ninja squad captain (who used to be Yuroichi's assistant) (Bleach)

Both use close-combat 1-hit-injure poison techniques.

Headphones Bounto using his doll's core (Bleach) VS. Bobby Max with a super sharp tennis racket (Prince of Tennis)

Both brute strength users. Bobby Max would own him.


P.S. During these fights, both opponents would be able to see/hurt each other (because normally, humans or regular ninja wouldn't be able to see shinigami without a byakugan)