Ash and his friends join Brandon in his flying Battle Pyramid and head for Snowpoint Temple, where something sinister is afoot. Legend says that long ago, Regigigas, Registeel, Regice, and Regirock saved Snowpoint City from destruction. Registeel, Regice, and Regirock then transformed into the pillars of Snowpoint Temple to protect Regigigas, who still sleeps within. Now, Pokémon Hunter J and her minions have invaded the temple to catch Regigigas; when they see the Battle Pyramid approaching, they send swarms of Pokémon to attack, forcing the Pyramid to make a crash landing! But with the help of their Pokémon, our heroes make it past the swarms and into the temple—too late! J has just destroyed the temple's three pillars, rousing Regigigas from its slumber.
Furious at being awakened, Regigigas starts to attack everything in its path. It emerges from the temple and continues its rampage, so Brandon has his own Registeel, Regirock, and Regice battle it: if he can capture it, that might calm it down. But as Brandon prepares to throw his Poké Ball, J snares everyone in Ariados’s webs and tries to catch Regigigas herself. Her failed attempt only makes things worse: now Brandon's Registeel, Regirock, and Regice won't return to their Poké Balls. Instead, they join Regigigas in its march of destruction!
J and her minions reassemble to try and trap the advancing Pokémon in a canyon. Once they have Regigigas snared in a sticky trap, J moves in for the capture, but Registeel, Regirock, and Regice leap to Regigigas's defense and are hit by J's special freeze rays. Ash and his friends get there just in time for Brandon to intercept J's next attack, but now Brandon is frozen too! All the commotion causes J's clients to cancel their request, so J and her men retreat. Regigigas calms down and unfreezes Brandon and his Pokémon before it returns to its slumber. Brandon promises to protect Regigigas: not only will he and Maria fight to defend it, his own Regice, Registeel, and Regirock will guard Regigigas by becoming the new pillars of Snowpoint Temple.