I'm not sure why you would need this but i would go with Arcei. Kinda like plural for platypus is platypi.
i think it would be just Arceus kind of like deer.
There is not an arceus trophy, and arceus was created after brawl, so arceus is not in brawl
Arceus has no gender.
arceus
Arceus.
no
Arceus.
arceus
ARCEUS
Arceus is not avabile. Right now, hack or use cheats to get Arceus.
Arceus has never been distributed as an egg. If you are referring to the egg from the HeartGold/SoulSilver Arceus event, it hatches automatically.
arceus is the alpha Pokemon
Arceus