Discarding Supporter

[clmnt]

If my opponent did not discard the supporter he/she used during his/her last turn, can my opponent play another supporter during this turn? The supporter is still remain beside of the active pokemon.

 

[PokePop]

We don't normally get into penalties and judge rulings, however POP has ruled on this.

This is just a messy game state issue.
A card that should have been discarded wasn't.
All that has to be done to correct the game state is to discard the card.
It is not appropriate to issue a severe penalty for such an easily fixed situation.
The player still gets to play their supporter.

Nothing stronger than a Caution should be issued for this and it would take many instances of this happening before escalating to anything stronger.
And even then, disallowing the player to play a card is NOT a penalty that can be issued.