I can imagine a Wario Land videogame with Wario and Captain Syrup like playable characters. It could be a Wario Land videogame but for 1 and 2 players in same time. What do you think about of this idea?
Something like that could work, certainly. There could be challenges unique to a co-op experience, whether they be working together to explore areas that require team effort or solve transformation-based puzzles that necessitate communication between two players to get the timing down. Assuming Wario and his partner played differently too, I'm sure the developers could make something special while staying true to the series.