In the anime, they are Brandon's most powerful Pokémon, with Regirock and Registeel using their power alone to defeat Ash twice. However, Regice was defeated later in Ash's rematch with Brandon. During Brandon's battle with Paul, each Legendary titan defeated all of Paul's Pokémon one by one. In Pillars of Friendship!, they were used to help protect Regigigas from J.
In Battling the Enemy Within!, Ash and his friends fall into some underground ruins by the Battle Pyramid. Inside the ruins Ash picks up a Pikachu statue which causes a boulder to roll towards them. They eventually run into Brandon who calls out Regirock to use Focus Punch and destroy the boulder. Regirock destroys the boulder and Brandon recalled it.
After Ash is corrupted by the King of Pokélantis, Brandon decides to battle Ash to save him. His choice is Regirock, while Ash goes with Sceptile. Regirock's key strategy is to defend, while using Lock-On to make sure its attacks hit the opponent. Although Regirock barely moved during the battle, it has both strong Attack and Defense capabilities. Even with a type disadvantage and a speed disadvantage, Regirock ultimately wins the battle.
In Overjoyed!, Ash returned to the Battle Pyramid to challenge Brandon. Brandon revealed that he would be using Registeel in the battle. The next day Ash sent his Torkoal against Registeel. Registeel was shown to be an extremely mobile Pokémon, as it was seen charging at Torkoal. Although Torkoal clearly had the type advantage, Registeel had incredible defensive capabilities and was able to evenly match Torkoal. Brandon's main strategy with Registeel seemed to be offensive and defensive combined into one. Although Torkoal managed to put up a strong fight and match Registeel in power, Registeel ultimately proved victorious.
Brandon used a strategy of freezing the field with Ice Beam to speed up Regice's movements and to do the complete opposite with Pikachu's. While Pikachu did land some hits with Thunderbolt and Iron Tail, it proved to be ineffective, as Regice trapped Pikachu in pillars of ice created by Ice Beam and then used Rest to fully recover any damage caused.
Regice then fired an Ice Beam towards Pikachu, completely freezing it. However, with the last of its energy, Pikachu broke free and delivered a final blow to Regice using his Volt Tackle.
A † shows that the move was used recently, unless all moves fit this case or there are fewer than five known moves.
Personality and characteristics
All three of the Legendary titans are considered to be very loyal towards Brandon as their Trainer. However, it was temporarily lost when Regigigas used Confuse Ray on them, which made the trio turn on Brandon. When Brandon blocked the attack from J's hand gun that could turn anything it touches into stone, the titans regained their loyalty. In most of the battles each of the titans participated in, they had no trouble taking on any opponent including the ones with the type advantage as seen in their battles against Ash and Paul, where they single-handedly defeated all of the latter's Pokémon in A Pyramiding Rage!.
During the battle, the three Pokémon used Superpower to contain the destructive energy created by the clash between Groudon and Kyogre. After Groudon and Kyogre are defeated, the strain of controlling the three Pokémon caused Steven to die from exhaustion. With no one to control them, Regirock, Regice, and Registeel lashed out against their controllers and left to parts unknown.
When Emerald challenged the Battle Pyramid in Chipping Away at Regirock, Regirock was the first to be sent out to face his Sceptile. During the battle, Regirock had its health sapped away by Leech Seed, so it countered by blowing itself up with Explosion, greatly damaging Sceptile. With Regirock knocking itself out in the process, Brandon switched with Registeel, who was sent out to face Emerald's borrowed Hitmonchan, Monlee. With his speed and super effective hits, Monlee was able to easily defeat Registeel, only to quickly fall by a Toxic attack.
The last to be used was Regice, who faced Emerald's borrowed Cubone, Bonee. Due to Regice's type, Bonee was at a disadvantage and was knocked out after a short time. Although confident that he had won their battle, Brandon was shocked to see that Sceptile had been revived in secret and defeated Regice with an Iron Tail, making Emerald the winner of the battle. In Skirting Around Surskit I, Regice was used to attack Guile Hideout in order to get revenge for Noland's injuries in the Artisan Cave. The attack did nothing to Guile, who simply swung his sword and sent Regice flying.