I have Punch Out downloaded on my Wii and just wondering if i can speedrun the game on this?

go for it. be warned that there is input delay even on the VC however.

99.999999% sure this wont make any difference for speedrunning in single segment (due to it being in-game time), so I say go for it, but like Jack said, input lag will make things tougher, especially Tyson. Im not so sure about the RTA categories however, there might be a slight difference between playing on console and VC in real time.

It seems like VC is usually a separate kinda sub category for each main category for other Nintendogs games but I guess it's just kinda up to the mods as always.

I have not played it on VC but I think salt has maybe(?) As far as I know the only difference is input delay so there'd be no reason you can't run it.