Amiibo exp

For character exp for Amiibo's would Amiibo's be a better choice or would a Level 9 cpu be a great substitute?

Level 9 CPUs are a bad idea, your amiibo will pick up bad habits like using air attacks.(ETC)

Speaking of exp, they should add an XP bar in the amiibo menu!

Amiibo should get exp from the trainer, training them against all characters of the roster for better results. Besides, amiibo will pick up bad habits from level 9 CPU and cannot learn beyond what the trainer can teach them.

Always train them yourself.

Just because you might not be good with a character, doesn't mean you can't train a good amiibo to be good against that character.