Nope, use the Cookie that raises the stat the pet uses.
Wanda uses S-ATK, Trim uses S-ATK and R-ATK, Sally uses T-ARK.
The only attack that seems to scale off R-ATK is Trim Bullet.
Unless I'm mistaken.
Your Switch skill only applies to your stats, and should be used if you're using anything other than Bouncer, Force or Techer as your subclass.
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