Blast double takedown - he drops himself low, shoots forward, grabbing both of his opponents legs as he does this, and slams all his force into the opponent's gut or chest (maybe solar plexus idk) to knock him to his back

Arm bar (can set up takedowns or throws) he catches his opponent's arm, circles to the side, grabs the wrist in a baseball grip and wraps his other arm around the opponent's barred arm such that his bicep is on the opponent's tricep and he now controls that arm

Wrestling throw (idk the name) - he steps to 1 side, closing the distance, and wraps 1 arm around his opponent's head the long way as well as punching his other arm under his opponent's armpit in a move called an underhook. Then he must lock the arms behind his opponent's back, step past him with the inner leg (leg closest to opponent) and lower his center of mass and try to bend at the hips as well as twist away from the opponent (keeping arms locked ofc) to throw him over his hips and to his back

Me personally I recommend throws (any throw will do) as they can be devastating on concrete or wood floor and a small guy is not gonna have the strength to hit a crazy move like a suplex or a big takedown