Keep in mind that visually separating out your cards in any fashion is illegal. This includes taking cards that are clumped together (like having 3 6-cost characters in your KO pile) and physically separating them.

There was a similar thread to this in the YGOrealms boards as well as on the YGO judge's list (with the reply by Alex Charsky), so unless it is changed, when you are shuffling, even between games, you may not know where any cards are at the start. So if you do get those clumps of 6-cost characters in your KO pile, make sure you shuffle really well. Everything must remain face-down.