You may wonder why Sonic and outside of it being my favorite thing,Mario and Sonic have been important to each other for a very long time.
Fans of both franchises have been waiting for an adventure crossover game, but all we got were olympic spin-offs and Smash Bros.
If we can't get a platformer,we might have to settle for an RPG, and I think that Davide Soliani and the rest of the Mario+Rabbids team can make that happen.
Plus, Ubisoft and SEGA have worked together with Yakuza DLC for Tom Cancy's Rainbow Six Siege existing.
I know what I said in the different parts sound like more of a new game than a DLC expansion, but why not make it a new game that's cheaper than both Mario+Rabbids games.
I'd call it Mario+Rabbids & Sonic as a reference to Sonic & Knuckles and the & Knuckles meme.
Speaking of Sonic & Knuckles, maybe since the switch uses cartridges then we could bring back lock on technology and if you lock on Sparks of Hope with & Sonic then Sonic could be playable in Sparks of Hope,and if you lock on with any other game then you would be treated with a remake of a no way screen with a new remix of the Sonic 3 continue theme with Rabbid Tails,Sonic,Mario,and Edge in the exact same order as Tails,Sonic,Knuckles,and Eggman respectively(Probably not though since the cartridges might be too small lol.)
A Sonic crossover DLC in a Mario game would make so much money that they might have to make an actual game that is not a Rabbids one,thank you for reading and make it happen for the third game.