9 stars are very impossible unless spending many tokens~
the new training system with fast trainner... and if you have enough green packs... 7 stars can be done... and at the end of the season, mostly will get several 8 stars (but promote...they become 7 stars again XD )...

my team right now, most for the players are close to 8 stars (one of my DC get 8 stars and my training LV 55) and even my two fast trainer i got 8 days ago... they are close to 7 stars already, the new training system some how train faster then the old system... but 9 stars.... well... it look either cheater or token buyer can do it~ (in same LV)