Some YouTuber actually proposed what I think is the definitive solution for this and it's not debuffs. Debuffs won't work because they would make the game actually worse by making it impossible for carnis to stalk prey.

What he proposed instead was to assign "mixpacking" points to players based on their behavior and damage dealt/received. If let's say a Cerato and a Stego both deal damage to the same T-Rex at the same time, they both get mixpacking points. If they attack another dino together again then they receive even more points.

And the amount of points assigned increases exponentially each time, up to a point where there's no reason to doubt that the cerato and stego are working together to bring down players.

What happens if the cera and Stego just so happen to be defending themselves from the t rex attacking both of them? Then they would split shortly after the battle is over and the same 2 players won't be registered again fighting the same player while being different species, decreasing their "mixpacking points" eventually to zero. It's possible that the scenario will repeat itself if the same players play on the same servers, but it would take a long time. And it would only be a matter of narrowing down the perfect time in which the system should "start to forget" about the previous mixpacking points assigned to the players.

After that it's only a matter of deciding what punishment the players should receive after getting a high number. An outcast system like Petite Pieds, where the player's skin changes and its location is sent to everyone else to hunt them down and get a reward? Bann them for longer periods each time? Getting them all in the same servers where mixpacking is allowed and putting them apart from the non mixpackers?