“Turns the ground into Electric Terrain when the Pokémon enters a battle. The futuristic engine within the Pokémon also boosts its Sp. Atk stat on Electric Terrain.”
Hadron Engine(JPJapanese: ハドロンエンジン) is a Pokémon ability introduced in the ninth generation. It is the signature Ability of Miraidon.
Description[]
Hadron Engine creates the effect of the move Electric Terrain on the battlefield as soon as a Pokémon with Hadron Engine enters the battle. The Electric Terrain lasts only for five turns. This can be extended to eight turns if the Pokémon is holding a Terrain Extender.
Hadron Engine also boosts the Pokémon's Special Attack stat by roughly 33% (or more precisely, by a factor of 5461/4096) on Electric Terrain. This boost will occur even if the Pokémon is not grounded. Skill Swap fails if either Pokémon has Hadron Engine.