1.(with grav hammer) turn them around, kick them to the ground.
As they attempt to crab walk away step up and two hand them in the face with the sharp side of the hammer.
Pick up the hammer with corpse attached and fling it off.
Takes a while, but would be epic.
2. (with grav hammer) Turn them around, wind up, and uppercut them into the sky Team Rocket style.
3. (with needler) flip around the gun, stab them in the back with all the needles, pull it out with them exploding a second later.
4. (with sniper rifle) tap them on the shoulder, as they turn around spin in a circle, holding the barrel, and crush their head in.
5. (magnum) buckles their knees, bullet to the back of the head mercenary style.