Can I place 9 damage counters on Walking Wake using its "Undulating Slice" attack if it would result in enough damage to knock itself out?
Yes, you can put up to 9 damage counters on Walking Wake even if it doesn't have that much HP remaining. Undulating Slice will do 20x each damage counter that was placed, and at the end of the attack Walking Wake will be knocked out.
Source:
Twilight Masquerade FAQ; TPCi Rules Team (2024-05-23)
If I use Greninja ex's "Shinobi Blade" attack and choose to search my deck for a card, do I have to take a card and put it in my hand if I don't find one I want?
You don't have to search, but if you do you must take a card and put it into your hand.
Source:
Twilight Masquerade FAQ; TPCi Rules Team (2024-05-23)
When I use Palafin's "Zero to Hero" Ability, do I shuffle both Palafin and the Basic Finizen cards into my deck, or just the Stage 1 Palafin card since it says to shuffle "this card" into the deck?
Only the Palafin goes back into the deck. Finizen stays in play, going underneath the Palafin ex.
Source:
Twilight Masquerade FAQ; TPCi Rules Team (2024-05-23)
Palafin ex's "Hero's Spirit" Ability is very literal. You can put it into play only with the effect of Palafin's "Zero to Hero" Ability; you can't put it into play any other way. The only exception would be if something like Hex Maniac or Garbotoxin are used, which remove Abilities of Pokemon that are in the hand.
Source:
Twilight Masquerade FAQ; TPCi Rules Team (2024-05-23)