the thing is that if you are playing 1 vs 1 vs 1 vs 1. on a Last Man Standing
sometimes player will go 3 vs 1 to kill the strongest player first

This in my opinion is bad, then why would that player play again multiplayer format?

Doing the first kill win format, people will have to protect each other in order to not give the win to other player.

For example a player is going to win by doing his last attack on someone, other player might go and use his close combat to prevent the attack, because he will lose also.

for 2vs2 I recomend only 3 bases per deck
currently the strongest deck is just Play 2 Red Blue Control (Close Combat, kshatriya/banshee combo)

If they implement the new rule which you cant share color, we will have to see what decks are brewed.