I'll send out Whimsicott @ Sun Stone.
Whimsicott: Grass Knot ~ Grass Knot ~ Grass Knot

Whimsicott: Grass Knot ~ Grass Knot ~ Grass Knot
IF (Rebound is used) AND (Colossoil is not under the effects of Taunt) THEN (use Taunt)
IF (Taunt is used) AND (Colossoil is not under the effects of Taunt) THEN (use Taunt)
IF (Taunt is used) AND (Colossoil is not under the effects of Taunt) THEN (use Taunt)