Warioland 4 would allow more possibilities for the bossfights, but it would be hard to code. Sonic CD would be preferred and would be relatively easier to code, but there are less possibilities for the bossfights. Donkey Kong Country would make more sense because the sequel is going to be like a 2d version of Donkey Kong 64, but it'd be hard to code and wouldn't allow many possibilities for the bossfight.