There should be spawn eggs for all the different variants of Mondans in the mod as if you want to have mondan with variant 3 to 17, you either have to summon using commands or find one in their natural habitats. 

Ah, I deliberately didn't do that as I didn't want to clog up the mob spawning with dozens of mondan variants. If I could code well, I'd make 1 spawn item that spawns all variants randomly