I wasn't even Shiny hunting and I just heard the Shiny sound and there it was.

Mine was the exclusive jirachi from the XD bonus disc.

Either my shiny alpha pachirisu or my shiny alpha chansey, both from mmos

I have a Zarude in GO.

Is arceus rare ( if logic wise then yes it is bc there should only be one and arceus has gone cloning and multiple people have him)

You can get 2 Arceus from bdsp and Legends arceus and Shiny Arceus has to be the rarest Pokemon so yes.

But how do multiple people have arceus

Prob just cheats or multiply glitches.

Mine is Flutter mane considering it’s scarlet exclusive and i have violet

Or a full-odds shiny paldean Taurus who ran into me and i didnt even notice it was a shiny

Wait you got Flutter Mane in Violet

Pls don't tell me you traded