Water Cyclone is the first exclusive ability for the S.H.R.IMP's mech in Plants vs. Zombies: Garden Warfare 2. When used, the S.H.R.IMP Mech will shoot out a cyclone of water in front of it to knock back and temporarily deal 5 damage to nearby plants.
This ability is basically valueless. Its only true use is to use it to push plants back to get away with Shrimpy Jump or use it against rooted plants. Though this will only work for rooted plants close to you and the Explosive Escape + Gravity Grenade tactic works much better than the latter. This ability should be mostly ignored since it also makes you an easier target while you're shooting the cyclone and although this does damage, it's very little so don't expect to get a vanquish with this. On maps like Boney Island or others that have hazards, this knocks plants back, so you could knock them in the hazard. Don't count on that, though.
You shouldn't have to worry about this too much except if you have low health. In fact, you can use this to your advantage because the mech stops moving while shooting out the cyclone so you can cripple his health down without it shooting back with the Shrimpy Beam. And it is very easy to dodge it before it fires the cyclone since he makes a mechanical/marine sound.