Originally Posted by MeanieRyuch
I'm fairly certain aggro is now based on who does the most damage, not who is closest anymore. This makes tanking slightly more difficult now...
From what I've seen, this seems to be true.
I was doing some experimenting while bossing. Making sure I was farther away from Chonpalm while my parter attacked didn't cause her to turn around, probably because I was doing the higher damage.
Also, my partner was the first to attack a Captain Johnny, and it targeted my partner until I used my 5th, which caused it to turn around and attack me. It never changed targets after that.