Ruby and Sapphire series
Electivire was eating an apple when Team Rocket attempted to capture it. When Ash was returning to Pallet Town, he encountered Electivire getting caught by Team Rocket, so he and Pikachu went to rescue it. However, Gary quickly arrived and had Electivire use Iron Tail to get out of their net and blast Team Rocket away with Thunder Punch. In Pallet Town, by Ash's request, Gary sent Electivire to battle Pikachu. The two sides clashed with Thunderbolt, then Pikachu closed in on Electivire with Quick Attack before both sides used Iron Tail to collide. Pikachu fired a Thunderbolt, which Electivire dodged, and used Protect to defend itself from Pikachu's Volt Tackle. Using Thunder Punch, Electivire defeated Pikachu.
Diamond and Pearl series
Electivire also appeared to help Gary and Ash sabotage Pokémon Hunter J's ship. When J's men went to attack Ash, they were intercepted by Electivire and Umbreon.
Encountering Hunter J, Gary sent Electivire to stop her, but Saturn's Toxicroak used Dark Pulse to counter it. As Hunter J was getting away, Electivire attempted to use Thunder, but Toxicroak stopped it.
Gary sent out Electivire to battle against a wild Moltres after his Blastoise fainted. When Electivire and Ash's Pikachu used their Electric-type attacks to weaken Moltres, combining Electivire's Thunder and Pikachu's Thunderbolt, the Flame Pokémon flew away while leaving behind a single burning feather for Gary to collect and return to the Project Mew lab.
With Professor Oak