If my opponent used Turtonator's "Shell Trap" attack and I have Espeon VMAX with the "Solar Revelation" Ability in play, will my Attacking Pokemon with energy attached receive the 8 damage counters from "Shell Trap" if I attack and do damage to Turtonator?
No, it will not receive the 8 damage counters. Solar Revelation prevents all effects of your opponent's attacks, and Shell Trap's damage counters are an effect of your opponent's attack.
Source: Fusion Strike FAQ; TPCi Rules Team (2021-11-11)
If my opponent used Turtonator GX's "Shell Trap" attack and I have Magearna EX with the "Mystic Heart" Ability in play, will my Pokemon with Metal energy attached get the 8 damage counters from "Shell Trap" if I attack and do damage to Turtonator GX?
No, it will not receive the 8 damage counters. Mystic Heart prevents all effects of your opponent's attacks, and Shell Trap's damage counters are an effect of your opponent's attack.
Source: TPCi Rules Team (2017-08-03)
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.
Source: TPCi Rules Team (2017-06-08)
Say my opponent used Turtonator GX's "Shell Trap" attack last turn, then on my turn I attack it with Shaymin EX's "Sky Return" attack. What happens to the 8 damage counters effect from "Shell Trap"?
Sky Return puts Shaymin EX into the hand as part of its attack before the damage counters are placed for Shell Trap's effect.
Source: TPCi Rules Team (2017-06-08)