Cellwind vs. Professor Shadow
Cellwind Vs. Professor Shadow is a crossover episode featuring the two titular characters battling it out for the Super Mario Odyssey Collectors Coin. Despite this, it introduced new faces such as the Disappearing Mercenaries and their leader, Samuel Hill, whom seems to be a recurring character in the universe now.
Cellwind has a beef to settle with Professor Shadow, and enlists Jack to help him out. Once arriving to Shadow's house, tearing through the Disappearing Mercenaries(including Guildencrantz & Rosenstern and Retarded Door Guy - excluding Sam as he's killed by Shadow), Cellwind confronts Shadow and fights him for a bit(with assistance from Joe and the Bolt-Action Rifle he had), eventually the two come to terms and decide to work together against a bigger threat. Little do they know, one Disappearing Merc will have unfinished business...
Despite the cliffhanger, a sequel does not appear to be in the works.