I love practicing against CPU 9s in 1v1 or even in free for alls a ton.
Some problems I have with them though is:
1.) In arena mode, they love to score on them selves (LOL).
2.) Sometimes they SD just to hit you or attempt it (mainly seeing this from falco).
3.) In arena mode, sometimes they love to attack each other and forget the sandbag even exists LOL (but when it's 1v3 in arena mode.. yeah they become savages..).
So really, the only change here some people may like and help people with TBH, is to make the CPU 9 a
little smarter (I guess?) so it's more
fun and
more challenging to play against (mostly for practicing in 1v1s).
Or at-least make it so their just smart/aware enough to not SD and spam up b like pit does and chibi robo spamming side b off the map and continues spamming b till he dies for some reason.
I do usually play against CPU 9 in 1v1 right after I do practice mode for a bit.
I'm sorry Idk how hard it would be to make the CPU 9 better, but I don't wanna sound like a bad person for saying this, just my opinion.