Awesome Pokémon. That’s all I can say.
Eternatus @ Choice Scarf / Choice Specs
EVs: 252 Spe / 252 SpA / 4 HP
Nature: Timid (+Spe, -Atk) / Modest (+SpAtk, -Atk)
Dynamax Cannon- Dragon STAB, already strong enough without the Dynamax boost.
Sludge Bomb / Sludge Wave- Poison STAB, you choose either better chance of poisoning target or higher base power.
Flamethrower- Coverage against Ice types.
Shadow Ball- Nice knowing you, Psychic types.
Pretty basic moveset, there aren't a ton of great moves for Eternatus to learn, but with the ones they can pull off, they’re beasts.