I believe the evolutionary stone you're referring to is actually the Shining Stone, and no; since multi-line evolutions are not supported at this present time, Pokemon can only evolve into one of their split evolutions, specifically the next Pokemon in sequence in the pokedex - in this case, Kirlia can only evolve into Gardevoir, but it doesn't have an alternate evolution capability in Gallade in PWO atm.
Ralts itself is currently uncatchable in-game - like most generation 3 Pokemon due to the absence of Hoenn in PWO presently - but it is available on the token store as indicated
here.
