Well when Riku is playable, two things are linked to it. The NPC of Xemnas with Sora Captured and the Xemnas Clone. Thus, if you use the party mod code and put them into the party, it would allow riku to be played.
Try This for the Riku code. Find the values for the Final Xemnas with Sora and the Artificial Xemnas that attacks you. With that, then modify it to appear on every map but in a location in which you cannot reach. Also, find a value to freeze the artifical Xemnas with the NPC Xemnas.
I hate both the 100 Acre Wood and Alantica. No Heartless and only Mini-Games. Pooh had amnesia basically and the singing was kind of annoying in a way.