You need to learn how to adapt. you need to actually think for yourself. if you are getting hit by bomb first avoid it then see what they do. if your far and they spam projectiles while jumping back and forth then combat it by pressuring them. get up close but be safe as to not get hit then try to punish their options.
another thing is to watch top players like zero and nairo how they play their characters and how they move. you have to consider that some moves are safe on shield but becasue you didn't know you get shield grabbed anyways, sometimes you don't know what to do in certain situations you can see how top players react this is why you should experiment in training mode see waht works and what doesn't work and memorize it and utilize the knowledge. you know you can only move so fast, and now its easy to do frame perfect moves becasue of the current buffer system. all that is left is the how do I get the most percent out of combos and how do I set up a kill
it doesn't even have to top player honestly, if you accidentaly do something then save it in your vaults then review the match you played
that's just a part of the fundamentals or you can pay for smash lessons if they are available but you won't be able to be as good as the top top players becasue they can figure things out super fast becase how much smarter practice than other people
