I have been telling my nephew, since he started searching on YouTube and found out about all the stuff Nintendo does to fan created games/mods, Nintendo isn't your friend, they are a business and they view IP as their life blood. Fans making content, especially if they begin to sell it, weakens the hold they have on it. They know this because they fucked someone over doing the same thing, so never expect mercy if you try to make playable or marketable fan content with Nintendo IP.
Enjoy the games but know they will fuck up your life if they think you are coming for their IP or sales money.
Edit: Fighting Force collection, I almost want to get that. I never got to play any version of the original. The sequel was ok but it wasn't a beat em up.