After defeating Ash Ketchum in a rematch battle, Brandon decided to go out looking for a specific Pokémon to capture in between episodes AG188 and AG190. While training with his Pokémon in the forest while waiting for Brandon to return, Ash Ketchum met up with Brandon who said he caught the Pokémon he was looking for in a nearby ruins. That Pokémon ended up being Regice.
Frontier Brain Battle VS Ash's Pikachu
In the final match-up of the 4-on-4 battle between Brandon and Ash Ketchum, Brandon's Regice faced off against Pikachu. Regice's movements became faster because the ground was frozen with its Ice Beam which slowed Pikachu's movements as well. Brandon's Regice was unable to dodge Pikachu's Iron Tail but it was able to recover from its injuries using Rest but that made it a bit vulnerable. Before using Rest, Brandon wanted to make sure that Pikachu wasn't able to counterattack by trapping it between ice pillars. Pikachu managed to break free with Iron Tail but wasn't able to deal enough damage to Brandon's Regice. Brandon used the same technique of trapping Pikachu between ice pillars while resting but the last time Pikachu's Volt Tackle hit its mark and Brandon's Regice was defeated. With that loss, Brandon was defeated and Ash Ketchum conquered the Battle Frontier.