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)
Gameplay » Win States
How do I win?
You win when you draw your last Prize or when your opponent loses his or her Active Pokémon and doesn't have a Pokémon on the Bench to replace it. You also win if your opponent can't draw a card at the beginning of his or her turn because his or her deck ran out of cards, but this doesn't happen very often.
Source: WotC Chat (1999-09-30)
Gameplay » Evolving/Devolving
How do I evolve a Pokémon?
You just play the evolved version of that Pokémon on top of the Pokémon you want to evolve. In other words, you have to have the unevolved version already on the table and the evolved version in your hand, and then you just put the evolved version on top of the unevolved version. You can evolve an Active or a Benched Pokémon.
Source: WotC Chat (1999-09-30)
Gameplay » Retreating
If my Active Pokémon has taken damage and I retreat it, does the damage go away?
No. Retreating does not remove damage. (But it does remove Poison, Confusion, Sleep, or anything else that's the result of a Pokémon's attack, including special attacks like Porygon's Conversion.)
Source: WotC Chat (1999-09-30)
Gameplay » Hand
How many cards can I have in my hand?
You can have as many cards as you draw. There is no limit to hand size.
Source: WotC Chat (1999-09-30)
Gameplay » Special Conditions
Do I flip a coin to see if my Asleep Pokémon wakes up at the end of the same turn that it fell Asleep?
Yes. You also [place] Poison damage at the end of the same turn a Pokémon got Poisoned.
Source: WotC Chat (1999-09-30)