Great part of the fun of PT is the leader power impact on the unit - so that's one big turn off.
There's also the issue of number of actions - it's easy to overpower someone with more actions and heroes.
Team oriented ideas
How about 1x2 but each opponent only play half of the turns i.e. P1-P2-P1-P3-P1-P2 then add one of the following:
A - The team of players share the same unit - but the leader is different on each player's turn to play (for simplicity sake they share damage - so they should pick leaders of similar health) - at the end of the turn the team swaps the leader.
B - Each player of the team has his own unit (they may either share damage or have their leader's health reduced to 50-75%)
FFA (this one is quite good)
For a FFA format I try to mimic Vampire The Eternal Struggle mechanic, first let's look at VTES:
1 - Similar play with deck limit (if it ends you simply don't draw cards anymore)
2 - The objective is reduce you opponent's influence pool (quite similar to leader health)
3 - You must ultimately destroy your Prey but you may also act against your Predator (whose objective is to destroy you) - hence aggression isn't necessarily unidirectional even tough you SHOULD crush just your prey (the more you weaken your prey the least he pressures your own predator)
4 - Each player has their turn alone (when they can play actions) but each other player may play reaction cards - actually this is quite different.
Let's see what to do
1 - Each player must target the player on his left and is targeted by the one on his right (his invader) - this is fixed and your objective is only to to kill your target's leader before he can kill your invader one - whoever defeats the target first wins - but you may target your invader heroes if they are putting too much pressure (just be careful to not overdo it)
2 - Each round all players play in the clockwise order but at the end of the turn the first player token is moved counter-clockwise. (so you usually are in defense position in relation to your invader)
3 - Deck composition - The simpler way is to have each player with the same set (quite feasible with print and play version or if you buy two sets)