I would personally go for Double Edge.
Sawsbuck gets STAB which adds a wicked boost. And with Horn Leech as recovery you don't need to worry about recoil damage.
With a base 100 Atk on Sawsbuck, 120 power from Double Edge, STAB and Band boost you're looking at a scary attack.
Double Edge: 180 base power with STAB
Sawsbuck: 492 Attack stat with Band