In Pokémon Colosseum...

[Shade the Light Gym Leader]

...can any one of the catchable Shadow Pokémon appear Shiny? Or do you have to trade from R/S/FR/LG to see a Shiny in Colosseum?

[Don't Run With Scizors]

I've never heard reports of a shiny being spotted in Colosseum, but then again, the chances of encountering one are extremely low.

However, the stats of the catchables are random - including some of the value that define shininess - so it's quite possible that any one of them could by shiny.

[The Muffin Man]

Actually a Shadow pokemon most likely has set DVs, so no it cannot be Shiny ever.

There ARE wild non-shadow Pokemon though. Those might appear shiny.

[rinku]

Advance generation shinyness is determined by the hidden individual value, not DVs as it was in metal generation.

Having said that, it is still possible that the hidden value is set.

But any random captures should have the normal shiny chance (something like 1 in 8000?).

[Don't Run With Scizors]

The DVs of the Espeon and Umbreon you start out with are random (except for the gender value; they're always male so as to ensure you don't breed them in RS to hatch a bunch of Eevees). And the gender values of all the other shadow Pokémon are also random (except for the e-Card with a shadow Scizor, which is male once again to prevent breeding Scythers), so why shouldn't the DVs and other of the shadow Pokémon be preset?

[rinku]

If they are always male, but their personalities vary from game to game, then the hidden individual (gender) value is only semi-set. So potentially you could get shinies.

If they always have the same nature then the gender value is probably a fixed value and no shinies will happen.

[Saturos]

Originally posted by Don't Run With Scizors
The DVs of the Espeon and Umbreon you start out with are random (except for the gender value; they're always male so as to ensure you don't breed them in RS to hatch a bunch of Eevees). And the gender values of all the other shadow Pokémon are also random (except for the e-Card with a shadow Scizor, which is male once again to prevent breeding Scythers), so why shouldn't the DVs and other of the shadow Pokémon be preset?

...Yeah, but unless you have a Ditto :P Like me.