Supports: Hank, Sunny, and Bucket.
Bucket pairs extremely well with Emet and Lazaurus since most of their healing comes from their healburst. Hank tends to be easy support to be effective with in general. Sunny can be pretty effective. Cabot and Kala are difficult to use supports that require an effective team.
Medics: Caira, Val, Rogue Val, Emet, Slim.
Caira has good healing with no particular weaknesses, Val has great single target healing but poor self healing, so she should be paired with a defensive support to cover that weakness. Rogue Val has great self healing, but poor single target healing, she can still keep a team alive but she has difficulty doing so. Emet pairs extremely well with Bucket, he has the most difficulty keeping a single target alive but can bring back allies from death with the respawn beacon. Slim’s healing is dependent on him shooting the monster so he can have difficulties with monsters that are capable of evading your damage while at the same time focusing down one of your teammates, I.E. he has some poor matchups with most namely the Kraken.
Trappers: Abe, Crow, Griffin, Electro Griffin, Maggie, Jack.
Abe and Crow have slows and good damage. Griffin Electro, Griffin and Maggie have harpoons which prevent the monster from moving away from their point of origin or pull the kraken toward them. Jack has the repulsor which prevents the monster from moving in a direction, or pushes the kraken to the ground.
Assaults: Parnell, Markov, R Abe. Not sure about Lennox, Torvald, Hyde or Blitz Markov.
Parnell has some great damage but is somewhat difficult to start using. Markov is one of the most consistent assaults in the game and doesn’t have any particularly bad match up. R Abe has poor damage but makes up for his poor damage with great after dome chase damage and a 5% damage dealt reduction debuff on the monster, works well in defensive team comps IMO.
Goliath: He is an effective monster with some good damage numbers. He tries his hardest to keep targets in melee range for melee strikes, or to setup for easy ability damage with rock throw, leap smash or charge.
Gorgon: She has a lot of easy damage with web blasts and acid spits as well as some CC with jetpack disruption on web blasted targets and her spider minions. Mimic deals a substantial amount of damage if your opponent can’t deal with it and you understand how to use it.
Kraken: A flying monster with a lot of firepower. Kraken’s flight allows him to evade a lot of damage that other monsters would normally succumb to, such as many of the games short ranged weapons, gas grenades, arc mines, and thunderstrikes. He can attack players from basically anywhere in the dome whereas every other monster must use abilities to attack from range. This allows him to keep up constant pressure on his opponents where other monsters need to reposition themselves to keep attacking whenever a hunter exits their melee range. Vortex gives him a quick cast for damage. Banshee mines give him good damage if not dealt with appropriately. After shock gives easy damage with a closer range requirement. Lightning strike acts as his main skill shot.
Elder Kraken: He loses the ranged attack and gains a melee oriented playstyle. He lacks good targeted damage IMO but has acceptable combat performance with chain lightning’s long chain distance, death spiral’s aoe over time damage, and his two skill shots: Lightning strike and banshee missile.
Monsters in General: If you are a good player willing to put in the work to learn the game, you should be able to do well with all of the monsters. With a possible exception to Behemoth who can’t be bought ATM.