Colossus and Mud have 3 illuvials which are only attained at Stage 3.
We should have 1 of the 3 from both be Colossus at Stage 2 and Mud at Stage 2.
So it would have to be this:
Greater Grilla would become Stage 2 Mud and Stage 3 Predator
Because we already have Adorius and Geyyser as Mystic Stage 3 so it wouldnt be Greater Aapon
Because we already have Ryplance at Berserker Stage 3 so it wouldnt be Greater Monkier.
either Titanor or Cardulox would become Stage 2 Colossus Stage 3 Granite/Toxic
Because we already have Archeleon as Verdant Stage 3 so it wouldnt be Gnarl.
These are extremely difficult to attain in Gauntlet Mode and would make the gameplay far more interesting, with different comps.
This will also make this more consistent with the pairing of synergies/classes in comparison to the others.