I had a thread about that awhile back, I still vote Naruto!!

Byakuya (bleach) - Kai (beyblade)
B'cause their personalities are pretty much the same:
they both show of because they really are good.

Oh, um.....Tomo from azumanga v.s. Yumi from azumanga
Loki from mythical detective V.S. Keal from wild arm T.V.
Tsume from wolfs rain V.S. Mr. Fluffykins (Sesshy) from inuyasha
and
Vash and Knive from trigun V.S. Sasuke and Itachi from naruto (Had to put in a brother throw down in there)

here are some more I thought of

Mugen (Samurai Champloo) vs Quzo *spelling* (Samurai 7)

Dark (DNAngel) vs Van (Escaflowne)

and a three way fox demon fight Shippo (Inuyasha) vs Kurama(YuYu hakusho) vs Naruto (Naruto)

how about shoenen bat (paranoia agent) vs itachi (Naruto)

Would be funny... and confusing

Ok.......Kakshi vs. Keitaro Urashima.......Kakashi would be able to attack for sure, but what do you do against and invinsible person.....

My little guy says:

Sasuke (Naruto) vs Armstrong (FMA) lol

weird....................

Jin (Samurai Champloo) VS Inuyasha

Karas(Karas) Vs. Naruto(Naruto)

Tetsuwan Atom vs. Megaman.



No contest, Mega would be doomed.