I don't claim to be good at the game...
But computers are rarely good practice.
I can often beat a level 9 CPU, but only if resort to very simplistic tactics... namely dash attacks the specials applicable, and close with a smash attack. Gimping, ariel combos, or any combo for that matter... and the like are doomed to fail. Oh and grabs... don't even bother as they will always be a tad faster than me and will mash out of it before I even realize I have them grabbed. I have been told, then agreed, that computers read our inputs and react... different than a player who has to see something happen on screen and react, or read what we are going to do and take the risk of being wrong.
This needs to be addressed in a patch imo... Smash is a mutliplayer game, but the single player should be useable training for multiplayer... not something that teaches bad tactics that most human's learn to counter pretty well, relatively early in their training.
In closing... they are a terrible measure of a person's skill so don't put to much stock into it.