What is the definitive source of rulings for the Pokemon TCG?

Question

I'm looking for what the definitive site for searching rulings for Pokémon TCG cards is, similar to MTG's Gatherer. Searching for specific cards comes up with various different answers, but most are reddit threads or Pokébeach threads.

As an example, I was looking for Decidueye-GX's ability Feather Arrow, to find out whether it was allowed to be used on the first turn or not. I found out it was, but not from anything looking official - just various discussions of the standard Decidueye-GX decks.

I'd like to be confident that my practice games are consistent with what a judge will rule in a tournament.

Answer 1

Official Pokémon ruling document regarding particular cards or their combinations is Pokémon TCG Rulings Compendium BW. It contains all rulings that were released by Pokémon Rules Team and approved by The Pokémon Company International.

If your card is not listed there, you can also look at similar mechanics, most of the time there is a card or a combination that fits your needs.

Your example of Decidueye-GX's Ability is covered by the TCG Rulebook though. It contains all the basic rules of the game.

• 3 ATTACK AND END YOUR TURN
  On the first turn of the game, the starting player skips this step. (...)

• ABILITY: An Ability is an effect on a Pokémon that is not an attack. (...)

You can use an Ability on the first turn of the game if it doesn't say that you can't.

Answer 2

From this answer, I found a link to the official Pokemon TCG rules (which can be found here).

This is probably as good as it gets for what you are looking for. There is an official card database, but it doesn't seem to have rule clarifications for cards.