You have to go through champion's road mode, and eventually you'll be able to buy a facility that trains Miis, you then give him two coaches which are your players, and then he'll gain certain attributes from each coach and the you play him through matches and he gains XP and earn's skills and get's better.
You'll need the player dormitory and the youth facility to do it, which becomes available after you win certain leagues.
Yeah, you will! U can train up to 3 Mii, but if you want superstars, you have to give him superstars trainers (upgraded with 6 full special abilities) and play in 5 stars difficulty....
But playing with a weak Mii on 5 stars level is a pain in the ass! :p It's well done though and a real challenge... u get marks for actions ur Mii did or didn't do during the match.... You have only 3 matchs to play for the Mii basic formation (after, you can still play with him for regular xp for special abilities).
Anyway, only played champion's road so far and enjoyed it a lot... have more than 200 players now in the team.... and am not done yet... :p
hahaha, 200 players! that's crazy.. I tend to release players as they become less useful. So when you first pick your Mii, do you get to choose his position, etc? Cuz when I import my Mii in Free Match mode, the game seems to just give him a position and stats (3 stars)
yeah, 200 players took me lot of times, but I still miss some I want! :p Even if you release them from your 32 players allowed team, you still can take them whenever you want from the dormitory (when you buy it)... About the position of the Mii, well, it will take the position of the 2 players you choose to train him kinda. More like a mix. And yeah, in normal match first time I tried to play with my Mii, I saw that too... random stuffs... But it's not the same.