Sure you don't want any bans? I'm not sure which, but i feel some restrictions are in order...
Pillars/pends must be of picked elements?
I quote this from the original rules:
4. Other rules
4.1 - Pillars, Pendulums and Standalone Mark cards
Every Pillars and Pendulums are always allowed in tournaments unless stated otherwise.
Standalone Mark cards belong to their element and is treat as the same as a Pillar for the purposes of official organized PvP unless stated otherwise.
About bans, I can't say anything yet, but expect many annoying cards being allowed because of the quite open meta.
Problem is that a fully upped deck is extremely faster than any unupped counterpart. If the 4-element players do not guess a very good counter versus their 2-element opponent, they are really screwed. In the end, the 'noobs without any upgrades' will be punched the hardest and that may even discourage any future participation to tournaments.
This is how upgraded tournaments went most of the time, but consider that a duo can be easier to counter with 4 open elements. The only problem is if the original choice of 4 elements is not wise enough, but that's a mistake that even veterans can make sometime. I also agree with Spielkind and Odii on the topic.