New dimension consisting of biomes from "oh the biomes we've gone"

Ive been trying to make a dimension for minecraft which just consists of "oh the biomes we've gone", but has no mob spawns or dungeons from other mods, however ive gotten to the part of creating the biomes in the dimension but have been unable to get them to work properly, the trees load, however biomes with special grass types just gets all those items replaced with stone, is there a way to do this so that it has all the same stuff it would when spawned in the overworld? if so please help