If its illegal to do such a thing then why is there a world-wide known game engine known as mugen where people can add in any various characters or screen packs that were wripped from an untold amount of console/arcade roms/screens ??
Link: www.maximummugen.hpg.ig.com.br/faq_mugen.html
Just because you can do it doesn't make it legal. I can smash somebodies face in with a baseball bat I bought legally. It doesn't mean it's legal to do so. Ok a bit of an extreme example but a valid one. Also if this kind of thing was legal the City of Heroes creators wouldn't have had lawyers all over them just because a few players made wolverine clones using their software. Link: www.maximummugen.hpg.ig.com.br/faq_mugen.html