Regice and Regirock are a pair of bosses fought in Epic Battle Fantasy. First, the party fights Regice, but it retreats after their battle. Afterwards, they meet Regirock, who also retreats, but then the party has to battle both bosses at once. Both bosses, plus Registeel, are derived from the Pokémon Legendary Golems.
During the battle with Regice, have Matt use Eruption, while Natalie uses Fireball. Then pummel Regirock with Matt's Airstrike, and Natz's Glacier. During the battle with both, focus your attacks on Regice first, then Regirock after Regice is defeated. You will obtain the Medal after the battle is finished.