While the Sploosh 7 is definitely a slayer, you can be an anchor, turfer or Pacifist with the main one. Using the subs wisely is key.
Pacifist Play Rocks!
Use a curling bomb to ink your way to an isolated area and swim then use Splashdown. This will ink turf faster than you can say "I'm a turf master!"
Abilities that WILL help!
While its damage is painfully high and its range just... poop, it is a great painter in itself. I would recommend the ability Ninja Squid so you can creep past enemies without them noticing (this is a staple in us Pacifist players). Pacifists often run away from conflict so Run and Swim Speed Up are useful. Then when in a pinch, You can fend for yourself, without main power up. For inking, ink resistance up is useful
Stay Away from the following Abilities
The ones will certainly negatively impact performance. One ability that is obviously a no-go in a Pacifist is Main Power Up.
Attack ups in general are useless, In my opinion, Respawn punisher is useless considering how you are trying to not get involved.