Say my opponent used Turtonator GX's "Shell Trap" attack last turn, then on my turn I attack it with Tapu Bulu GX's "Tapu Wilderness GX" attack. Does "Shell Trap" place its damage counters before or after the healing part of "Tapu Wilderness GX"?

Tapu Wilderness GX heals Tapu Bulu GX as part of its attack before the damage counters are placed for Shell Trap's effect. So in the end Tapu Bulu GX will have 8 damage counters on it.

Relevant cards

SMA_SV52

SMP_SM32