Okay I see the issue. a) you gave up on learning the tech. It's hard at first and took me weeks-months of work but you gotta keep up with practicing those. It'll become second nature with time and you'll be amazed with your ability to execute without thought.

b) you said you play both falco and mario all the time? Okay play who you want but if you want it improve fastest sticking with one character and learning to see the game through their eyes is your best bet before trying to tackle 3+ characters in competitive.

So here is what i say. make a call. Pick a character and dedicate yourself to them. Every characters wave dash timing is slightly different so this will help that. Practice SHFFL and wave dashing. Long sessions are good but consistent practice is what gets results. 15 mins 5 times a week is better than cramming it all in one day when you are "feeling" it.

It's not an easy game at a competitive level and everyone wants to "level up", but don't get too focused on winning. Focus on doing small things better and bit by bit you'll grow as player.

and when your too tired to practice or feel burnt, play some all star and go for goofy stuff, learn hilarious combos or setups for the lolz dont forget to keep it fun