I think in the God Rugal CVS2 scenario, Rugal witnessed it, survived it (thanks to Orochi powers) and that’s why he was able to copy it. Well Rugal copies moves from people all of the time. Obviously CVS2 is in some alternate universe (and no matter what scenario you get, Rugal dies and Gouki lives) but I think you have to at least witness, experience or have been taught the move to be able to do it.
Of course in martial arts anime/manga/games this isn’t always the case. Ki/chi/fighting energy can make you speak into people’s minds (DBZ with Goku saying ‘I need more power’ in the movies, Naruto vs. Sasuke fight) communicate with trees (Ryu Final), and allow you to speak to the dead and make you figure out stuff you were never taught before (Hokuto No Ken AKA Fist of the North Star). I’m not exactly sure how this works in SF land.
At least I ‘think’ the way Dan did SGS in the comic isn’t possible in the games. It WAS funny though and when it comes to comedy anything goes.