Honestly, I use brawlbox for just about anything on smash, even PSAing. It is, in my opinion, easier to use, and a little more forgiving (I tend to get freezes alot with psa).
Now enough with that, if anyone knows what the heck I am saying.
For your first hack, if you don't have one already, I would do a texture hack, because psa and model replacing are a bit challenging if you don't know what you are doing. Plus, you will be way less likely to freeze your game.
If you want to start making movesets, here is a link with a tutorial: