Prinplup has been through the care of my pokesave, but I guess this gives me an excuse to breed it again.
I did Riley's Riolu after Mesprit and Cresselia.Asside from the fact that I had to advance 900 frames (I wanted Inner Focus instead of Steady Fast) , it was sweet and un-complicated - no NPCs to mess up things. Just help him through the cave with your party full and when you are close to the exit he will offer you the egg, but since the party is full, he wait for you to have space for it, so you can prepare, leave a poke behind, save in front of him, check seed, advance the frames and talk to him. =)