This is the toughest Colosseum you'll be in, since all the pokemon will be Legendary Pokemon, and fully evolved pokemon, this is also where you'll face Yoshi, Kanna, Sashay, Joe, Kruger and Mysterial one last time. Which means there will be 6 sections in this one. Prepare yourself, this will be your final pokemon battle, these are the orders of when you'll face them:

1st Section: Joe

2nd Section: Kruger

3rd Section: Sashay

4th Section: Mysterial

5th Section: Yoshi

6th and final section: Kanna

Those are the sections, I hope you caught some legendary pokemon and your pokemon are fully evolved, since only fully evolved and legendary pokemon are allowed.