User blog comment:Tyrone851/An Epic Battle With The Very Best Fire Users and Also What Character Do You Want For Project Versus J/@comment-1044263-20130110210220

Rin has to few experience, Ace IS a beast, but I think he'd be defeated by Natsu, since Ace's flames will have little to no effect against Natsu... Natsu will also eventually defeat Tsuna, though that would be an epic fight. *O* But in the end, Yamamoto pwns Natsu~

Also, Natsu and Gray won't be in "Project Versus J.", cause the game is for Shōnen Jump like you said, and FT isn't in Shōnen Jump.