If I use Absol's "Cursed Eyes" Ability to move three damage counters from one of my opponent's Pokemon to another, what happens if I choose a Pokemon with the "Theta Stop" Ancient Trait?
Since Theta Stop prevents all effects of Abilities done by your Pokemon, if you choose to move the damage counters to a Pokemon with Theta Stop the damage counters would be discarded rather than moved onto that Pokemon. However, if you choose a Pokemon with Theta Stop as the source of where the damage counters would be moved from, they simply are not moved and the Cursed Eyes ability stops there.
Source: TPCi Rules Team (2015-09-03), TPCi Rules Team (2015-09-24)
If a Pokemon with an Ability also has the "Theta Stop" Ancient Trait, would it prevent Wobbuffet's "Bide Barricade" from stopping that Ability?
Yes it would because Bide Barricade is an effect that is targeting the Pokemon, so Theta Stop would prevent Bide Barricade from blocking the Pokemon's Ability.
Source: TPCi Rules Team (2015-09-03)
If I use Mega Sceptile EX's "Jagged Saber" attack against Giratina EX with the "Renegade Pulse" Ancient Trait, does Mega Sceptile EX's "Theta Stop" Ancient Trait prevent "Renegade Pulse" from blocking the damage? If not, then does "Renegade Pulse" prevent "Jagged Saber" from attaching any Grass Energy?
Renegade Pulse prevents all effects of attacks done to Giratina EX, but it does not "do anything" to Mega Sceptile EX for its Theta Stop to kick in. So the damage part is blocked by Renegade Pulse, but the effect of attaching energy is not being done to Giratina EX so that part of the attack does not get blocked.
Source: TPCi Rules Team (2015-09-03)
If Sceptile-EX has its Spirit Link tool attached, but Banette's "Tool Concealment" Ability is in play, what happens if you evolve to Mega Sceptile-EX with the "Theta Stop" Ancient Trait?
Theta Stop prevents the effect of Banette's ability against Mega Sceptile-EX in time for the Spirit Link tool to turn back on and not make you end your turn.
Source: Ancient Origins FAQ (2015-08-13), TPCi Rules Team (2015-08-13)
Does Golurk's "Double Type" ability which says "As long as this Pokemon is in play it is both {P} and {F} type" block Flareon's "Flare Effect" ability or Vaporeon's "Aqua Effect" ability or Jolteon's "Electric Effect" ability which adds {R} or {W} or {L} to any stage 1 Pokemon?
No. Golurk would have all 5 types if all of those Abilities were present.
Source: Ancient Origins FAQ (2015-08-13), TPCi Rules Team (2015-08-13)
If Flareon's "Flare Effect" ability or Vaporeon's "Aqua Effect" ability or Jolteon's "Electric Effect" ability adds Fire or Water or Electric type to a Darkness Type Pokemon, does Dangerous Energy get discarded since it says, "If this card is attached to anything other than a {D} Pokemon, discard this card"?
No, it is not discarded. Even with the addition of another type to the Darkness Pokemon it is still also a Darkness Pokemon.
Source: Ancient Origins FAQ (2015-08-13), TPCi Rules Team (2015-08-13)
Can I use Ariados' "Poisonous Nest" Ability if both my and the opponent's Active Pokemon are Grass type?
No, you cannot.
Source: Ancient Origins FAQ (2015-08-13), TPCi Rules Team (2015-08-13)
My active Arbok uses its "Gastro Acid" attack against Weezing with the "Aftermath" Ability. Then on my opponent's turn he uses Weezing's "Smogbank" attack to do 20 damage to each of my Pokemon. If I have Latias-EX with the "Bright Down" Ability on my bench, would it take damage or not?
Since Weezing has no Abilities due to Arbok's attack, it would do 20 damage to Latias-EX.
Source: TPCi Rules Team (2015-05-07)
If Banette's "Tool Concealment" ability is active, can I attach multiple Tool cards to my Pokemon?
No, you cannot.
Source: Roaring Skies FAQ (2015-05-07), TPCi Rules Team (2015-05-07)