Gameplay » Win States
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)
Gameplay » Win States
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)
Gameplay » Special Conditions
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)
Gameplay » Special Conditions
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)
Gameplay » Knock Outs & Prizes
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)
Gameplay » Deck
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)
Gameplay » Cards in General
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)
Gameplay » Knock Outs & Prizes
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)
Gameplay » Win States
At the end of a long match, I Selfdestruct Magneton. My opponent and I both take our last Prize cards. Who wins?
Well, if one of you has a Benched Pokémon to replace your Active Pokémon and the other player doesn't, then the person who can replace his or her Active Pokémon wins. Otherwise, you play Sudden Death. This is explained in the Pokémon rules in the Expert Rules section under "What Happens if Both Players Win at the Same Time?"
Source: WotC Chat (1999-10-04)