Enemy Pokémon taking less damage

I have been running a list with Radiant Gardevoir and have noticed either in play or not in play my enemy will get a bonus of taking less damage. This is a recent deck I started using but even double checking everything on the board, I can’t find a reason for them to take less damage.

ex: attacking with Arceus Vstar doing 200 damage to Raiku V.

this should KO but instead it does 180. Even if I don’t have radiant Gardevoir on the bench. It could be in deck or discard.

I started planning around this by adding a choice band to Arceus and this brings the attack to 210.