Electivire is available in Pokemon Sword and Shield's first DLC pack the Isle of Armor.
Here's how to evolve Electabuzz into Electivire!
Electirizer
Electivire's Bulbapedia page states you must trade an Electabuzz whilst holding an Electirizer for it to evolve.
Previously Electirizers were found in a dungeon.
Although it may not be the same in the new DLC.
