It comes with the Suction Bomb and Killer Wail. In Splatoon 2 it comes with Curling Bombs and Splashdown. It has the ability to ink the ground while on the move. The weapon can also fling ink at a medium-length range. If you roll into an enemy while using it, the enemy will be crushed. The roller also doesn't cover as much ink when making a u-turn.
"A weapon adapted from an ordinary paint roller. Aside from inking the ground, it can also be swung to hurl globs of ink at your opponents."
The Splat Roller is a standard Roller which is faster at inking than the Dynamo Roller and spreads more ink than the Carbon Roller. It is therefore better suited to spreading ink than combat though it can be used offensively. Ink will be sprayed outwards when the trigger is pressed which can splat an opponent quickly at short range. Suction Bombs can also be used to force opponents out of areas to aid in reclaiming turf. The Killer Wail also fills a similar role.
Tips against each weapon type
Shooter-type weapons are not usually a problem on their own but can be troublesome when there is more than one as it can prevent you from getting close enough to splat them. Some blasters are also a problem with their high attack power and range. Throwing out a suction bomb before entering enemy territory or going round a corner will expose ambushing blasters.
Roller-type weapons can be a problem with exception to the Inkbrush and Octobrush weapons which both can be outranged. If two splat rollers attempt to squish each other, both will be squished which is not always the best solution. Trying to squish a splat roller at an angle can sometimes result in victory but it is risky. A good tactic is to hide in your ink and wait for a surprise attack if you see another roller coming. Then jump in the air, look down, and press the trigger repeatedly and avoid being squished.
Charger-type weapons are usually fairly easy to deal with as the suction bombs and killer wail can force charger users off high ground making them vulnerable in the open. Chargers are usually less able to splat you at short range so getting in close is often a good idea. Don't attack a charger head on however as this will make you an exposed target.