Some players freely examine their own discard pile (or their opponent's) whenever they want. Is this allowed? Or can a discard pile only be examined when you have official business there (like after playing Item Finder).
Discard piles are open knowledge (either player could look through them).
Source: WotC Chat (2000-04-06)
If my opponent had 3 cards left in his deck and I used Wildfire to discard the three cards, on his/her next turn do I win?
Yup, you would, if someone cannot draw a card at the start of their turn like they are supposed to, they lose.
Source: WotC Chat (2000-03-09)
If I draw my last card. It is an Electric Energy so I use Raichu's Gigashock and it kills all of my opponents. Who wins?
You do, because you won't actually lose for being out of cards until the beginning of your next turn.
Source: WotC Chat (2000-02-24)
My opponent attacks my Active, which causes 20 damage and Poisons it. Her turn is over. Do I then have to put 1 more damage [counter] on it because it is still Poisoned?
Yes.
Source: WotC Chat (2000-02-24)
If you use an attack that puts your opponent's Pokémon to Sleep (like Haunter's Nightmare), and the Defending Pokémon was already Asleep before you attacked, do you still have to flip a coin after the attack to see if it wakes up?
Yes, they get to flip at the end of each player's turn.
Source: WotC Chat (2000-02-10)
If one of your Pokémon was Poisoned, and a few turns later it is KO'd by the Poison, does your opponent take a Prize card although the Poison KO'd the Pokémon, and not your opponents Pokémon?
Yes, he would still draw a Prize card. Whenever a Pokémon is Knocked Out, the other player gets Prize cards -- even if you Knock Out your own.
Source: WotC Chat (2000-02-10)
Are you allowed to have as many DCE as you want in a deck like normal Energy or only four like any other card?
Only 4 maximum, it is NOT a basic Energy card (the only type you can have more than 4 of in your deck).
Source: WotC Chat (2000-01-27)
Are Promos legal in tourney and league play?
Promo cards are legal in tourney and league play [As long as they have been released in the local area].
Source: WotC Chat (2000-01-27)
When you Knock Out more than one of your opponent's Pokémon in a turn (i.e. using Selfdestruct or Raichu's Gigashock attack) do you receive a Prize for each Knocked Out enemy Pokémon?
Yes you do. And if you knock out some of your own, your opponent gets to draw prizes as well.
Source: WotC Chat (2000-01-27)