W and up arrow - jump. a and d or left arrow and right arrow - move. s and down arrow - attack. same thing to the OG's but when bf is killed you see he is down and when Sans is killed then you see Sans down. And one more change. the powerups.
Thanks to KalamattoWasHere for the original project Undertale vs Friday Night Funkin and thanks to RememberNovember for the original project BattleRena (2 Player).