From Inkipedia, the Splatoon wiki
The Octobrush itself is a frontline slayer.
- It has 2 modes: Swinging and Sliding.
- Swinging the brush will fling ink. Mainly used for painting, charging special, and fighting.
- Sliding will hold the brush to the ground and run fast. Mainly used for mobility and dodging shots.
It also has a few weaknesses.
- Its short range makes it weak against longer-ranged slayers.
- A lack of bomb also makes it so it lacks a poking tool against long ranged anchors and worse in fights.
- Its ink flings lose damage quickly, even making it from a three to four shot splat at longer ranges.
- It also has a slow firing/swing speed compared to other slayers. Along with the aforementioned bad falloff rates, this is bad because most other slayers have a faster firing speed and range.
Squid Beakons are situational, but are sometimes good.
- Squid Beakons can be used to quickly get back in the game after respawning.
- Squid Beakons can also be used as a safe escape tool if the player is wearing enough Sub Power Up or Quick Super Jump.
- Place Squid Beakons in safe spots where enemies have to expose themselves and be vulnerable to destroy, such as behind your cover.
Ink Storm can also come in handy.
- Ink Storm can be used as passive painting for control. It can be used as a throwaway on the Splat Zone and then lets the player pursue enemies while it slowly takes zone.
- Ink Storm can combo with the Octobrush Nouveau's damage. However, it does move slower than its roll speed, so the player will have to slow down for combos.
- Ink Storm can also be used as a quick ink refill for when the player runs out of ink.