Better indicator of whether or not you've already defeated a trainer

[SebastienGllmt]

You can check their name and then compare it your achievement list, but this is a little tedious

[RadinEth]

Undefeated : same as now

Defeated: color is blank

Also the "crystals" over the trainers could simply stop spinning. You could also remove them but players would get confused as non-trainers NPC doesn't have "crystals".