As part of the Ubisoft Forward event for September 2022, Davide Soliani, creative director of Mario + Rabbids: Sparks of Hope, announced that the upcoming Switch title will be getting a Season Pass that will offer up a new batch of post-launch content. While a lot of this remains unknown at this time, it was mentioned that one of the DLCs will be framed around another iconic Ubisoft character.
As for who this character will be, fans can look forward to a DLC framed around Rayman. There's no mention of when Rayman will arrive, but just take solace in the fact that soon you will be able to use Rayman in Ubisoft Milan's adventure-strategy game.