Trusts

[Canadane]

They will always be the same. They will be synced down to the dungeon level just like you are when you enter a lower dungeon than your level.

Nah they can level up. They'll sync down if they level too much but there's a range of 2 levels per dungeon.
They do slightly better if they level up from what I've seen.
But it's barely noticeable, it's not like they're the best as it is.