Got one right on my first cap as soon as the event started, so I'll do a quick write up.
Gerbera/Tiger Pierce has excellent speed and quick cancels making it a very combo friendly rock. No down / up hit, but it has plenty of side hit making it suitable for use as a straight melee rock.
Tactical Arms 2: Bow Form has 3 rounds, with above average damage, and good reload. Initial weapon shot time is lengthy which makes it hard to acquire and land a shot with auto-aim, if you free hand this is not a problem obviously. With OS up, the reload rate is near instant, so it becomes a pretty spam happy option when you're near death.
Tactical Arms 2: Sword Mode is a vast improvement over the Blue Frame Tactical Arm's version. It still carries the slow, but has very strong forward arc coverage, if you hit someone with it, they'll generally eat a full combo. Forward length is about 2 suits, if not a bit more. The # of hits works exactly like Blue Frame Tactical Arm's does. 3 hit stages, 3rd knocks down but if you end early it doesn't count against your five hit limit.
I'll probably make a video some time later this week, provided someone else doesn't get one by then and make one on their own.