I sometimes play with a guy named Mike. He's a complete noob, who plays Marth almost exclusively. But, he has one thing going for him...
His grab. It's weird. It doesn't matter if it's an FFA, a 1-on-1, or a team battle. He'll grab, seemingly at random, and in situations where you wouldn't normally even think to grab. In spots where a smash attack, tilt, spot-dodge, roll, shffled move, or wavedash would have been appropriate, he'll grab instead. The weird thing is, it seems to work like 90% of the time.
We call it, simply... The Mike Grab.
(Not really a combo, but thought it was worth mentioning.)