They don't have a choice in the matter. Nintendo/Game Freak is the one calling the shots.
Oops, I forgot about that, lol. A shame really. Everyone has their tit for tats with the show. Promotion is just something that should be toned down, IMO.
Like Team Rocket had great Pokemon, I hope Seviper never leaves, such a shame, Arbok, Dustox, and Chimeco, as well as Lickitung had too.