I want to see if I'm understanding Snatch correctly, it seems that it acts like Constrict if the target is small enough. Constrict deals additional damage on successful grapple checks, I think Snatch works the same on certain creatures.
"Snatch: The creature can start a grapple when it hits with a claw or bite attack, as though it had the grab ability. If it grapples a creature three or more sizes smaller, it squeezes each round for automatic bite or claw damage with a successful grapple check."
So if a Gargantuan creature hits and grapples a medium or smaller creature with a bite/claw, it does damage immediately because of Snatch, right?
Then in the following round when it successfully maintains the grapple, it can choose to damage the target as part of the maintain grapple check, and also squeeze for more damage from Snatch?
yep. and if it can also gain constrict its added on top. just hope they don't have power attack as the damage is usually build off the claw\bite attack damage so power attack is added (as combat maneuvers are attack rolls)