If the peak objects are gone, no Riolu. If you put the minimum required for Riolu, Nosepass will appear since the blocks are maxed out. At this point, you're going to have to try hitting all your target frames with Riolu at different slots. For example, you tried slot 8 and it appeared at none. Try removing all the plains objects, since you don't need them. Riolu will be at slot 5 then, so try all your frames and see if it shows then. My guess is if you remove the plains objects and hit the frame that gave you the level 48 Nuzleaf, it'll be Riolu because the Nuzleaf was supposed to be slot 5.