Probably when you trade Pokemon over from Colosseum and Leaf/Fire to R/S, you get certain decorations attached to certain Pokemon.

The Kanto starter giant dolls probably are attached to those Pokemon when traded over, and the same goes for everything else. :/

R/S and Colosseum are still the best, but, being the fanboy I am, I will buy Leaf/Fire.

Besides, you get that nifty wireless linkcable, which works with other games, too.

*Imagines wireless battling in the bus, car, mall, restaurant, etc. with his friends*