Ecogym (Neo Genesis 84/111)

Whenever an attack, Pokémon Power, or Trainer card discards another player's non-Colorless Energy card from a Pokémon, return that Energy card to its owner's hand. (Energy cards that are discarded when that Pokémon is Knocked Out don't count.)

Card rule

This card stays in play when you play it. Discard this card if another Stadium card comes into play.