Puffers don't really have the killing instinct that the other Predators do. If you were to put a large puffer in with a large dovii.. The Dovii would be much more quick and agile, and instantly lace into the puffer (and probably stun himself) but make him puff up immediately. Granted, Puffers have the biggest bite of any fish, pound for pound (FW), but they don't have that berzerk go out and attack anything mentality.
If you consider it a matter of weight, you have to look at the Snakeheads body shape in comparison to most other predators. He is going to weigh less but be just as viscious at maximum size. Red Devils, Dovii's, Umbee's will all weigh a considerable amount, in comparison to a slender bodied giant snakehead.
I would be more interested in the match verse snakeheads and perhaps a lungfish, but lungfish don't have that berzerk attitude either. Big difference between a 'large predator' and 'a crazy whacked out bite your face off predator'..
Just a few things to think about. I am sure we are not considering alot of factors, so I don't know exactly who would win. I heard Aba Aba knifes are quite nasty too, and as long and streamline as they are, they will not weigh as much.
I would go with Channa, Dovii, Aba Aba.. I guess ?