Step 1: Be Masashi
Step 2: ???
Step 3: Profit!
Really, don't expect to last long against high-level players without using advanced techs unless you're Masashi or Aniki, or one of those Japanese smash geniuses. In order to get good at this game at a competitive level, you have to practice, learn, and master some essential skills.
It's like how I was with music. I used to wish I was better at the clarinet, but I never wanted to practice, and I was hoping to get better without learning to play in all keys and use proper finger technique. It didn't work, so I ended up practicing for years, and now I'm pretty **** good on clarinet, and even ended up being good at sax too, using the same tenacity for improvement. It's the same with smash. Put in the time, master the essentials, and you have the potential to be an amazing player. And maybe with what you learned from playing Fox, you could get good with some other characters too.
If you read all of this, can I ask why you weren't practicing? JK, if you don't want to use these skills, you don't have to, but don't expect to be good without them.