The Deoxys mission in Guardian Signs was an event-only DLC mission. It is no longer available for download as of January 2011.Why does everyone forget that you can get as many deoxy as you want from the last pokemon ranger game. The only legendary you can not get is Arceus Darkrai. besides that very one of them is getable
Also, Darkrai is obtainable at any time forever through the tweaking glitch on D/P.