(for synavy, one of Witzke's OCS) This game dosen't have any gen 4 or below pokemon minus two legendaries Ho-oh and Lugia, and the only other pokemon that aren't from gen 5 is Pikachu, Raichu, Eevee and it's eeveelutions.
Left side bosses are: Kyurem, Kurem(white form), Kyurem(black form), Ho-oh (can also be found shiny), Lugia. Caution: If you are using Hydriegon(is recruited after game completion) lugia knows dragon rush and dragontail. Smackdown dosen't seem to affect Kyurem's Fly attack (white and black forme included) Kyurem knows dragon tail (and so does lugia) there MAY be some other pokemon... (even though i did beat the game, and i know i didn't see pokemon from gen four or three) (huge spoiler: To recruit melloetta, you must beat the game, and have you (pokemon self) return to paradise, and build the musical Paradise (is like the Sky Jukebox from explorers of sky, but there is a huge difference) and i do not recommend to be Pikachu, because you cannot find a thunderstone.

(unless you want to risk it and get volt tackle...(would be great if you can get eggs, because volt tackle is alittle bit like take down, and i do want a pikachu with aggron's ability, so that i can use recoil moves without the recoil affect....or To have a sap sipper sesmitoad.... reason: no swampert... :'( ) )

Snyvee: sweeeeet.

Really no Gen 4 & less (except a few exceptions) That's odd. Why would they do that. Well, still sounds like a great game. Hyper rank xD I could imagine that.