Sky Pillar & Mew

[MCRFamEx]

Does Sky Pillar stadium stop from placing damage counters on opponents bench Pokemon, for example Mew UNB 76 attack Psypower?

I believe it does stop this attack even though it is placement of damage counters, as it says it prevents effects and damage.

If it does prevent this, in the event a player announces placement of damage counters on a bench Pokemon is this then negated and they can correct and place instead on active or do those attempted placements on bench get blocked by Sky Pillar and player (without Opponent's permission) is not allowed to correct this and cannot switch it's decision of where to place damage counters?

Game play action question:
When is damage counter placement or if assigning damage to chosen benched Pokemon considered to be final and not reversible (without permission from other player)?

Mew's ability:
Lastly, Mew's ability Bench Barrier does it stop the placement of damage counters like in Mew's Psypower attack? I thought there was already a ruling with Mr. Mime that "Bench Barrier" ability doesn't stop placement of damage counters to bench Pokemon, but was unable to find in Compendium so wanted to clarify.

Thanks,

MCRFamEx

 

[PokePop]

Yes, "all effects" includes placing damage counters, so that would be blocked.

They would not be allowed to change their target without your permission.
The Benched Pokémon were valid targets for the attack and were legal to be chosen, is just that the effect was blocked.
So if they did choose them, then the attack is blocked and wasted.

Bench Barrier does not stop effects that place "damage counters".
It only stops Damage.
So if it is phrased as "10, 20, 30...", Bench Barrier blocks it.
If it is phrased as "1, 2, 3...", it does not.
There should be a ruling on the concept somewhere in there but I'm not sure off hand where it is exactly.
Might be a general "placing damage counters is not the same as doing damage ruling"

Found this under "*Attacks in General":

Q. I've noticed that some cards say "Does 10 damage to the Defending Pokémon", whereas others say "Put 1 damage counter on the defending Pokémon". Is there any reason for the different wording? I've spoken to someone who says that you do not apply weakness or resistance for attacks where it specifies Damage Counters; is this the case?
A. There is a difference. As you mention, weakness and resistance are not applied when placing counters. Also, things like Defender and Metal Energy will not block Placing Damage Counters. It will not trigger things like Base Set Machamp's Strike Back. In the steps of resolving an Attack, "placing Damage Counters" counts as an Effect of the attack, it is not part of "doing damage". (Sep 18, 2003 PUI Rules Team)​