I've been playing a few Super Famicom versions of games released in the USA and here are three sad cases of massive butchering: The three Rushing Beat games, released in the USA as Rival Turf, Brawl Bros and Peace Keepers.
All three had their intro, endings and credits butchered or removed (even if they were in English already). The only one that at least retained a lof of its original content was Peace Keepers and even that one had a completely ridiculous translation in stead.
Actually, the Jaleco translation director said (according to a FAQ author that got in contact with them) that when they translated the Peace Keepers, they pretty much made up the whole story because Jaleco of Japan never gave them any assets to work with.
Rival Turf, which is still kind of lame, feels a lot better with the cool intro and more fleshed out ending. The USA version feels very bare bones with everything removed.