You have to get azure Flute to get Aruces. You get the azure flute in the market in Jublife or in Canalve City. You will see the green guy and he will give the azure flute. Then you go to the Spear Piller (where you catch Pal,Dia,Gira) and you and you go straight until it says: "The azure flute is making sound would you blow the azure flute?"and you click yes. Then the glowing stairway comes out and in the top there is Aruces. You can catch it with hyperball.
you cant he is only in diamond pearl and platinum
You have to download the azure flute from mystery gift.
you can enter codes for those Pokemon by buying an action replay cartridge for Nintendo ds. { can be found at EB Games, GameStop Ebay.com and other places.}
to use it you have to go to the place where you catch Digla,Palkia and Giratina. Once you stand on the trangle thing in the first place you use it and then u cna battle Aruces at lv.70 ( i think the event is over 0.o)