Whenever I rack up enough damage on my opponent, I always keep my beam fully charged and whenever I land a grab, I down throw and then tag them with the charge shot. It's a great KO.
When I'm trying to rack up damage with a grab, I just down throw, and then up tilt, which is a good set up for more juggling.
A good set up that I use for grabbing is to wait for an opponent to move towards me on their feet, and then drop a bomb and stay close to it, keeping it between me and the opponent. Usually they'll stop and wait for it to explode before advancing, or they'll stop to use a projectile, giving you the perfect opportunity to grab. Also, if they don't stop and instead try to jump over it, be ready with a Nair or Uair into a smash missile.
With very aggressive characters, I like to crouch, waiting to land the down tilt, which knocks them up enough to quickly jump up into a Uair, which gives perfect knockback (at most percentages of damage) to tag them with a smash missile before they even land, and the missile usually works as a lag cancel too.
These are just off the top of my head, I hope this is useful.
Another easy combo is simply to have your beam fully charged and then fire a smash missile and then immediately fire the charge shot. This usually works out for me in two different ways. Either they shield the missile and then release it quickly to move, not having time to shield again before the charge shot hits them, OR the missile connects knocking them back (off the ledge is great) and then the charge shot comes in and KO's them before they have a chance to regain control after the first hit. You have to mess with your timing with this move depending on whether or not you're trying the first way or the second way.
Here's a kinda cool one. When I knock someone off the stage but I know they're going to recover, I'll wait near the ledge (usually works best on an opponent who is coming in from underneath), and then run off the ledge, quickly drop a bomb, and then DI back into the stage without using a jump. Immediately start charging a down smash A, so by the time the bomb connects, it sets them up in the air right in front of the ledge ready to eat your down smash A.
Here's a completely useless move that I figured out. I simply came up with it just to be a total ******* to my opponents. With a fully charged beam shot ready to roll, I wavedash backwards off a ledge to keep my opponent from being able to grab it, but instead of simply watching them fall to their death, or worse get screwed by a good up B like Marth's, Link's, etc., I push down to drop, then immediately jump, quickly tilt away from the stage toward my opponent and release the stick, and then fire the charge shot for the KO, which also knocks you back enough so that you land on the stage. At first you might not do it with the right timing and the charge shot won't fire fast enough to knock you back onto the stage, so you'll just have to be ready with an up B to land you back on the stage. If you do have to use your up B, use it as fast as possible because if you take too long you'll end up facing the wrong way and not grabbing the ledge. Gotta do it early enough to actually land on the stage. After you get the timing down though, you'll be able to use the charge shot to knock you back onto the stage and not have to worry about the up B. Again, this is completely pointless, but it looks awesome and it's a great way to be a total ******* and piss off your friends.
I just joined this board so I don't know if this is all common knowledge or not, but I came up with it all on my own (knowing very well that every other Samus player most likely uses these techniques, or uses better ones), and I'd like to know what you guys think. Practical, effective, better for 1v1 or free for all, doesn't work on certain characters, etc.?