Which monster are you playing?
Goli is the most well-rounded, however if you don’t capitalize on his mobility then the assault can really tear you up while trapper keeps you down. Decent at S1 fights, but only if you can escape with 1-2 downs and minimal health loss.
Kraken just needs to stay airborn, and is overall decent, but you really have to land combos if you plan on downing hunters. He should not engage in a S1 fight.
Kelder is up there with Goli, but you really have to stick close to the hunters if you want to get downs.
Wraith is a glass cannon. She’s either extremely effective (usually her balance is dependent on the hunters picks) or complete trash.
Behemoth is strong, but you need to pick your fights in locations that benefit you like caves, not open areas, and gotta use combos to burst hunters down. Also pray that you aren’t facing Slim.
Gorgon is the mix between Goli and Wraith. She’s best if you play her like Kelder though, sticking to the hunters and unleashing chaos. Hard to pick up as a first monster, but extremely useful once you have the basics of being a monster (i.e. feeding routes, focusing medic/support first, and knowing what abilities are better than others).
But that’s just for Monsters. The other half of the equation is what platform are you playing on, and what hunters are you facing? Laz works well against Kraken and Wraith, while Slim destroys Behemoth. Knowing your opponent is knowing how to win.