Briefly, why would you want these 2 specific mutants in that area? Well you need both of them at the same time to get one of Nina's School dolls and to get a Golden Apple that requires a TK to activate a telekinetic switch in the area before Nina's School.
This method requires 2 controllers
How to do it: Take the route from the Ratcicle Kingdom to the area with the Ice Prison Arena where you need a TK to scale up the wall and get a RhinoRoller (from level 8) of the arena battles. (or if you haven't unlocked the ice battle arena because you didn't free the Ratcicle Boss from the ice in the cave then bring a RhinoRoller from the Desert/Wastelands)
There's a TK that should be at the bottom of the wall, put your Rhinoroller in your pocket and it should appear, kill it and jack it or if it's already jackable then jump on it.
Now the guys in the forum here said that at some parts you can't scale up the wall with the TK because you cant press RB to get higher altitude as the rhino is in your pocket and so you just switch to that when pressing RB, it was said that to counteract this problem that you just need to jump with a RhinoRoller and then switch in mid-air with a TK and he'll grab onto the ledge, this method did not work for me, either it's a non-working method; you guys got lucky or it's just too difficult
, but either way the method I'm giving will work everytime without fail
and is not very difficult, which is why I decided to post this.
Before scaling the wall, make sure your on your TK and the 2nd controller has already pressed B to join the game, you should see COCO standing near you. Now switch to your RhinoRoller with your first controller and press B to jump off it. Now quickly before it dies grab your 2nd controller and with COCO jump onto the RhinoRoller.
That's the hard part over, now with your first controller (making sure you leave your 2nd controller turned on, but do not touch it or move it or do anything with it) scale up the wall with your TK and just forget about your 2nd player on the rhino, it won't die, disappear or in any other way vanish.
Once you reach the top of the wall keep going left to the exit the area, use a heavy attack (hold Y while on your TK to smash the ice) and once the loading screen has gone by you'll be in another area.....yes.....the Ratcicle Kingdom!! and COCO WILL BE THERE ON A RHINOROLLER, SLOWLY ROLLING AROUND, SUCCESSS!!!!!!!
Now being quick and confident, press B with your 2nd controller to dismount COCO from the RhinoRoller and quickly jump back onto it with Crash using your first controller. Now you can drop out your 2nd character and turn off the controller. With both mutants in hand, head as north as you can go in the village and with the RhinoRoller open both the doors to the pathway to Nina's School..... you're in!