Gen 9, Tera Raid attacker
Miraidon @ Magnet
Ability: Hadron Engine
EVs: 252 HP / 4 Def / 252 SpA
IVs: 0 Atk
Modest Nature
- Metal Sound
- Electro Drift
- Parabolic Charge
- Electric Terrain
Miraidon is a bulky, fast, hard-hitting, and self-healing Electric special attacker who overlaps multiple effects to help both itself and its allies deal more damage faster.
Hadron Engine automatically sets Electric Terrain upon entering the battle. This not only increases Electric damage and protects against Sleep for you and your allies, but also directly increases Miraidon's SpA (another effect of Hadron Engine) and activates allies' Quark Drive (in particular: Iron Hands is a popular Electric-type choice).
Metal Sound increases both your and your allies' damage by sharply decreasing the opponent's SpD. It should be used once on the first turn. Note that it will not work later when the raid boss puts up a shield (4+ star raids only) as it is a status move.
Electro Drift is Miraidon's signature move. It has high base power (100 Pow) and perfect accuracy (100 Acc) with no negative side effects. Moreover, Electro Drift deals ⅓ more damage (×1.33) when it is super effective in addition to to the regular type effectiveness multiplier (×2.0).
Parabolic Charge is for healing yourself (50% of the damage dealt) during longer fights. Since the amount recovered scales in proportion to the damage dealt, the healing also benefits from type effectiveness, STAB, terrain, stat changes, Miraidon's legendary-tier base stats, held battle items, terastalization, etc. Also, it does still simultaneously charge your Tera Orb since it is a damaging attack (vs. a status move or cheer).
Electric Terrain is for resetting the Electric Terrain that your Hadron Engine originally created. This should only ever be necessary in really long fights, but it is important to do considering the significant benefits to both you and your allies (see original paragraph above). It also increases your self-healing by increasing the damage of Parabolic Charge.
The max SpA EVs, Modest nature, and Magnet (item) are all designed to maximize damage output while simultaneously sustaining your own HP (through Parabolic Charge). HP EVs are maxed instead of Spe because longevity is more important in Tera Raids than first-mover advantage. Atk has zero IVs to minimize damage from Foul Play.