No, like other legendary pokemon, arceus does not have an evolution. the closest that you can get to evolving arceus is by giving it plates which change its color.
Evolution is a process, theories of evolution are theories which explain that process
It is called "evolution".
Spontaneous evolution is evolution that is not moderated by intentional beings and actions. Most evolution, in other words. Usually we call non-spontaneous evolution (ie. evolution that *is* moderated by intent): breeding.
it is the "action" in evolution
EVOLUTION
Arceus.
It doesn't evolve or have a pre-evolution
That's unknown. Arceus is already too strong as it is now, it doesn't need a Mega Evolution, and holding a Mega Stone would prevent the use of the Multitype plates anyway.
Like an Arceus without it's yellow thing or a Cobalion
There is not an arceus trophy, and arceus was created after brawl, so arceus is not in brawl
Arceus has no gender.
arceus
Arceus.
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Arceus.
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ARCEUS