Brock and Onix were shown in an advertisement, as the former declared he would take on the challenges in his Gym. Red took on the challenge, and defeated many challengers to have Brock battle him. Brock had Onix fight against Red's Pikachu. Pikachu failed to dodge Brock's Onix's Rock Throw, and started attacking Red instead. Brock became angry, seeing how Red only won the previous battles through luck. Onix used Skull Bash, which hit Red and Pikachu. Pikachu, who was moved by Red's words, electrocuted Onix, who split into pieces, thus making Red win the Gym battle.
Since Jasmine sent a Steelix, Brock mistook it to be an Onix and sent his own Onix. Onix used Bind on Steelix but it was hurting itself, causing Steelix to reveal its true look. Steelix used Crunch, which knocked out Onix, and Jasmine revealed that Steelix used to be an Onix too before it evolved.
|Rock Throw||Onix is On!|
|Skull Bash||Onix is On!|
|Slam||The Winged Legends|
|+ indicates this Pokémon used this move recently.*|
- indicates this Pokémon normally can't use this move.