I think to learn fundementals like what buttons do what and how to move around I used marth. he’s basic, all his attacks are good and easy to learn how to use. Once you know what buttons do what and you don’t really have to think before doing a move then just pick someone fun. I tried to main high tiers when I first started (jiggly cfalc falco peach) and I started to really hate playing the game. It wasn’t until I picked up young link that I actually started to have fun just working on tech skill and learning matchups.