What are all the factors that affect the confusion damage when a battling Pokémon is confused?

Question

Aside from standard damage modifiers e.g. 2x Attack from Swords Dance and basic facts/stats like the typeless base-40 damage.

Comments

I’d like to add, that since it is testable, there’s no reason why a detail should be ignored.
It’s different if it’s something untestable, but this is.
In this case, it should be able to be tested on showdown.

---

Marvel Scale doesn't affect confusion damage, it only affects major status ailments.

---

Marvel scale ACTIVATES when there's a major status ailment. It AFFECTS physical damage, which may or may not include confusion damage.

---

Well, since Confusion is somewhat hinted at being a Physical hit, Marvel Scale should affect Confusion.

---

Abilities that raise physical attacks (like guts or pure power) don't affect confusion damage in some generations, so it's definitely possible that marvel scale is also like that.

Answer 1

It doesn't seem to be affected by marvel scale:
https://replay.pokemonshowdown.com/gen9anythinggoes-2082923083
(both dragonairs in the replay were the exact same besides the ability and item)

I also tested eviolite and metal powder, they don't seem to affect it either.
https://replay.pokemonshowdown.com/gen9anythinggoes-2082929091
https://replay.pokemonshowdown.com/gen8anythinggoes-2082931200

For all the other factors this info is in the comments and bulbapedia:

Confusion damage is calculated as if it were a typeless physical move with a power of 40; it cannot score a critical hit, and does not receive STAB. Confusion damage is unaffected by Wonder Guard, Technician, and a held Life Orb. Badges affect confusion damage when they boost the user's physical Attack or Defense. It ignores burn and Technician as well.

Source: https://bulbapedia.bulbagarden.net/wiki/Confusion_(status_condition)

There is a table on the bulbapedia page for some things that work differently on different games.

Hope this helps.