Not sure anyone has already mentioned this or not, but POG is super fun using more than on character to fight...plus a potential increase in player involvement because there's motivation to level more than one toon.

What I'd suggest:
1) Improve the maps for POG so that there's more than just one map/path

2) Increase the number of characters in the fight to come closer to matching the number of player characters which is around 12 atm I believe.

3) Have battles between players where they can use more that just one toon to fight.
Then give rewards for accounts that win these POG pvp battles, and have a ladder too of course.