Is MegaMan Voulnutt a robot?
No, he’s human. That’s not to say he has always been human, but he’s human now. Mega Man Legends 2 (if you can believe anything it says, given how the plot has enough holes to be a sieve) states specifically that MegaMan transferred his consciousness into a carbon’s body (carbons are humans). This explains things like why he requires a Rebreather device to go underwater.