The rules clearly states that video evidence of the run is required so no.

As long as no mods are involved of course

I have seen multiple runs with the alternative skins on being verified (including me) so yes.

Sonic Generations (2024)

Another Note For Moderators: Is Changing Skins Allowed Like, Sonic Adventure Modern Sonic And Sonic Jam?

Death egg robot 

Black-Shadow

Submissions will be available 2 weeks after the official release (November 8th). These 2 weeks serve to help the moderation team create main categories, the IL leaderboard and respective rule-sets. Until then feel free to join and help the community with your findings and personal bests on the freshly opened SXS Generations-[Discord](https://discord.gg/M6CyCfC6M7)!