I think that the three (in the order Torvald>Sunny>Slim) have got abilities that turn the game into something more frustrating.
Torvald + sunny/hank/bucket + Laz? Jumping everywhere like a crazy grasshopper, trying to spread the damage while your hp melt (if your HP doesn’t melt, you’re playing against a bad Torvald, if he can foresee who’s being attacked, he can trade damage). Good luck in defeating Laz without good damage spread or some kind of body camping. Spreading damage with Hank is almost impossible, you’ve got to take damage while focusing him down, and then let Laz revive him while you immediately focus on Torvald, with sunny you’ve got to take dmg to destroy the drone, or throwing a fist here and a fist there, with bucket you can’t easily destroy the turrets without risking mortar rounds, and Laz + Torvald means you’re full of weak spots, the kind that turrets love the most.
Slim + everyone? Grab a chair and sit closer to your TV. Or boost the gamma, but I hate playing like this.
Sunny is already forbidden in some tournaments, and she’ll surely be nerfed again, but I bet that Torvald would be the choice 99% of the times, if not for the Kraken.
Releasing an hunter that is OP and frustrating against ANY other monster than the most powerful one… Meh.
I hope that the 5th monster won’t be another flying one, otherwise people would feel pressed to buy it.