Completing sonic riders zg for the third time even if it's my least favorite of the two (free riders can kick rocks) and it's got me in the mood for sonic stuff in general plus writing-
My personal headcanon is that the sonic riders games are in a separate more relaxed universe than the main line games.
Eggman is a mad scientist/business man. Only partially bent on domination.
Everything's all high tech and futuristic way ahead of everything in the other games (minus that one level in forces). Knuckles is a treasure hunter but the mission mode has Eggman mention the echidna tribe and master Emerald so that's probably still a thing. Sonic's still a free spirit and tails is a mechanic.
The guest characters make sense if you view Billy and ulala as humans and ai amigo as just mobians respectively.
Nights i like to view as a mascot turned sentient ai projection who took up racing for the fun of it. (Pleasing fans instead of dreams)
Project shadow definitely could have happened here so shadows fine
Silver and blaze are really the only ones who mess things up