It boosts the power of Electric-type moves used by affected Pokémon by 50% (regardless of whether the target of the move is affected by Electric Terrain). This boost includes moves that became Electric type due to type-changing moves like Electrify.
If a Pokémon is holding an Electric Seed while the field is Electric Terrain, it consumes the Electric Seed and its Defense is increased by one stage (even if it is not otherwise affected by the terrain).
If a Terrain Extender is held when Electric Terrain is used, the terrain will last 8 turns instead of 5.
When a Pokémon with the Ability Electric Surge enters battle, Electric Terrain is automatically created which lasts for 5 turns (8 if the Pokémon holds a Terrain Extender).
If powered up by an Electrium Z into Z-Electric Terrain, the user's Speed stat is raised by one stage.
The power of Electric-type moves goes up. It also prevents Pokémon from sleeping.* It changes the floor to the Electric Terrain condition. In this condition, Electric-type moves get more powerful. It also prevents Pokémon from sleeping, but it has no effect on Pokémon in the air.*
In the anime
Hurting the opponent
The user electrifies the ground under everyone's feet, increasing the power of Electric-type moves.
Manectric's body becomes covered in yellow electricity, and it fires a beam of electricity from its body at the opponent. The electricity then forms into a dome-shaped cage of electricity around the opponent. When the cage appears, it will hurt the opponent, and if the opponent touches the cage, they will get hurt again.