Cashuea
Inuyasha would win. Yep, nothing like a half-deamon to kick some tush! xd
Ryu is a god beast and thus cannot die.
He'd be re-encarnated at the dragon statue. Inuyasha would fight him over and over untill that one night, and as we all know ryu is cappable of learning time adjusting magic (as is his first spell in breath of fire 2) so he could warp time untill inuyasha was human and kill him then and their.
Not to mention, as in ryu kotse dragonscales are invenurable to the windscar and Ryu wouldn't have to use any energy attacks so he wouldn't have to worry about the backlash wave.
Ryu Wins hands down.