I don't know if the other two are Events (I'm certain the Giratina I have is caught in-game), but I MIGHT have a Dialga and Palkia. I'll have to load my PC while doing some breeding 2morrow and investigate. I might be thinking of something else (like the Regis, I know I have all four of those), and as I type now I don't think I have the other two mascots, but I'll check when I'm back on that game.
I really should check my used Pearl and see if it's a completed game...
Well, I already have a Giratina, and I already have a Griseous Orb (the question is whether your Giratina is untouched, the one I received is up three levels from the catch point and I know I can someday put in the untouched one).
As for the others, I have the Shiny Lv.5 Larvitar Event. Yanmega...may interest me; I have to see if my Yanma knows AncientPower, and if so, it'll be there in one level. If not, it saves me the trouble of using Heart Scales. I think my Yanma was caught JUST as it forgot AncientPower in the moves learned list.
So depending on the stats of it, the Giratina is possible (with or without the Orb, I guess with wouldn't hurt), and the Yanmega is a backup option.
Do you accept clones for the Event Legendaries (Entei in this case)? It's already been used for an Event in Lostlorn unfortunately (before I had Action Replay, same thing with my Celebi in Castelia) but I can still trade it.
I also have Lv.1 Zoruas that already know Night Daze, their signature move. Two full rows with different natures in my PC. If you are happy to train them yourself (they get the Lucky Egg boost automatically when traded, useful with an Exp. Share when leveling someone else!), I can send one along. Moveset is Leer/Faint Attack/Foul Play/Night Daze. (No, they are not hacked; I just know how to breed them correctly.)