Board Thread:General Discussion/@comment-32710969-20190209215847/@comment-27123436-20190209234735

M.U.G.E.N. is a fighting game engine, there is no canon as it's just the skeleton for building your own game. However, there have been games released with that engine like The Black Heart. You could consider crossovers between M.U.G.E.N. characters like the fans of the RPG Maker indie games do, with Moge-ko from Mogeko Castle meeting Mary from Ib and such, though there's no canon to it.