Brandon caught Regice shortly before Ash challenged the Battle Pyramid for the last time. Regice battled Ash's Pikachu but although it put up a feirce fight, and almost defeated Pikachu, it was eventually defeated by Volt Tackle. Regice is arguably the weakest of Brandon's legendary Pokemon as it is the only one that has been defeated on screen.
Regice appeared again in A Pyramiding Rage, where it defeated Paul's Lairon in seconds, despite its type disadvantage and battled his Ursaring before being recalled.
Regice was also used to battle Regigigas, but was confused by the Colossal pokemon's Confuse Ray and went on a rampage along with Regirock and Registeel. When the evil pokemon hunter J attempted to capture Regigigas, Regice, Regirock, Registeel and Brandon were all turned to stone in order to protect it. After J left due to her client cancelling the deal, the Regi's and Brandon were revived by Regigigas and stayed at Snowpoint Temple in order to rebuild it and guard Regigigas.