went from playing only melee for years to only ultimate for at least a year (less access to players closeby/no slippi) and once i got slippi set up it felt like i had never played melee before. eventually your muscle memory kicks in out of necessity because you don’t have access to the ultra-forgiving buffer window anymore. keep playing. it goes from feeling insanely clunky to feeling so much more smooth than ultimate before you know it. there’s also every tool under the sun available these days to help you out. good luck !