Nero

Used as a taunt tank in Arena and Special Interception. Each time healing applies, Cat's Repayment1 stacks reduce damage taken, and once stacks are full, her Burst opens an all-enemy taunt and the Big Cat state.
She rarely makes story or Raid core teams. Healing-over-time ticks alone do not build stacks well.

At battle start, Lil' Paw2 raises max HP. Each time healing applies to an ally, Cat's Repayment1 stacks, reducing damage taken for both the healing ally and herself.

Using Grumpy CatB after stacks are full deals damage to the enemy with the highest HP and taunts all enemies. She then enters the Big Cat state, increasing HP recovery received, and counter damage may apply when hit.

When hit, there is a set chance to apply increased damage taken to the enemy. Her Burst cooldown is 20 seconds.

Use Burst after Cat's Repayment1 stacks are full to open the taunt and Big Cat state.
Fill Cat's Repayment1 stacks in teams where ally healing comes often.
Auto is basically fine, but in Arena, watch healing timing alongside the healer's Burst.

Assumes a B1 healer in the same squad. Other healers like Rapunzel may only overlap in slot. With Nikkes that only have healing-over-time ticks, stacks build slowly.

Prioritize Resilience Cube to cut Submachine Gun reload. Support sustained fire with Bastion Cube. Max HP ties into tanking, so Vigor Cube is the next option. If Harmony Cube levels differ a lot, use the higher-level cube before following the ranking.

As a Defender, prioritize Increased DEF lines. Use remaining lines on Max Ammo for fire density. ATK and Elemental Advantage damage matter less for her tank role.

Cat's Repayment1 stacks are the gate to her survival, so raise S1 first. Grumpy CatB's taunt duration grows at levels 4 and 7, so for Arena, bring Burst to 4 or 7 before going further. Lil' Paw2's max HP comes from S2.

Used as a taunt and damage-reduction tank in Arena and Special Interception. She is sometimes added as support only for bosses where cover matters or survival-heavy phases. She is rare in Union Raid and Solo Raid core teams.

Each time healing applies, Cat's Repayment1 reduces damage taken.
After stacking, her Burst taunts all enemies and boosts healing efficiency in the Big Cat state.
Lil' Paw2 greatly raises max HP from battle start.

With Nikkes that only have healing-over-time ticks, Cat's Repayment1 stacks build slowly.
Her taunt is tied to her Burst, so allies can get hit first before Burst.
In teams without a healer, her tanking value drops greatly.