Oddly enough, I do have Saga in front of me right now.
As a Standard Action, you can make a Grab attack against an opponent up to 1 size category larger than you. You take a -5 penalty on your attack roll, and it's an unarmed attack (which means it provokes an AoO if you don't have Martial Arts I; however, taking damage from the AoO doesn't spoil the Grab).
If you hit, your opponent is Grabbed. Grabbed opponents take a -2 penalty to all attacks with non-natural or non-light weapons. It also cannot move. Breaking a grab is a standard action which automatically frees you from CL grabbers.
If you have the Pin or Trip feats, you can make a Grapple attack against an opponent up to one size category larger than you as a Standard Action. You make an unarmed attack (again, c.f. Martial Arts I) at no penalty, and if you hit, you and your opponent make Grapple checks (which, in SWSE, use the better of Strength or Dexterity).
If you have Pin, your opponent is held in place, loses their Dex bonus to Reflex Defense, and can take no actions at all for one turn (barring an Escape Artist check to escape, depending on how you read the rules). If you have Pin and Crush, you deal unarmed strike (or claw, if greater) damage each time you pin your opponent.
If you have Trip, your opponent falls prone in their square, taking the normal penalties for being prone.
If you have Trip and Throw, you may instead move the target into any empty square up to 1 square beyond your own reach in any direction, and the opponent takes unarmed strike damage.
In lieu of using Pin or Trip, you may instead deal damage with a light weapon.