Which Pokémon deals the most damage in one Attack? Dialga or Eternatus?

Question

Dialga signature move (roar of time) have 150 base power and Dialga special atk is 150.
Eternatus signature move (eternabeam) have 160 base power and Eternatus special atk is 145.

My question is: Which attack really does the most damage to a Pokémon hp ? (Eternatus,Dialga and the other Pokémon is at lv 100)

Both attacks looks powerful, is it possible to one hit K.O Arceus ?

Comments

https://calc.pokemonshowdown.com/

Answer 1

(Note Dialga and Eternatus have had their bulk altered to match each other)

0 SpA Dialga Roar of Time vs. 0 HP / 0 SpD Eternatus: 229-271 (67.1 - 79.4%) -- guaranteed 2HKO

0 SpA Eternatus Eternabeam vs. 0 HP / 0 SpD Dialga: 237-280 (69.5 - 82.1%) -- guaranteed 2HKO

Eternatus is stronger than Dialga. It won't OHKO Arceus if it's specially defensive:

252+ SpA Choice Specs Eternatus Eternabeam vs. 252 HP / 252+ SpD Arceus: 297-349 (66.8 - 78.6%) -- guaranteed 2HKO

But Eternatus does have a shot if Arceus was physically defensive instead:

252+ SpA Choice Specs Eternatus Eternabeam vs. 252 HP / 4 SpD Arceus: 397-468 (89.4 - 105.4%) -- 37.5% chance to OHKO

Comments

Thank you S2