The anime is not the main Pokemon universe, people who reference that feat are usually just giving away the fact that they don't know what they're talking about
Arceus is canonically the creator of the universe; no matter how much you dislike it that doesn't make it any less true. It's a universe level being with dominion over multiple universe level beings. Thor is blinked out of existence, that's all there is to it.
In an in-game event Arceus spontaneously creates either a Palkia or Dialga, aka the Pokemon with control over all space and time in the universe, or a Giratina which the existence of an entire dimension is dependent on, and the game even says this is Arceus giving a glimpse of its true power, as Arceus is the creator of everything. Whether or not Arceus has universe level power is honestly not a question.