Gameplay » Retreating
If I have Zubat (no retreat cost) as my Active and retreat him, can I bring him back as Active or do I have to bring up another Benched Pokémon?
When you retreat a Pokémon, you are swapping it (a switch) with another on the bench. So in this case, Zubat goes to the bench, and you bring up a different Pokémon from your bench.
Source: WotC Chat (2000-02-17), WotC Chat (2000-05-11)
Gameplay » Special Conditions
If my Pokémon fell asleep and it wakes up next turn, will it be able to attack on that turn or the next?
You flip at the end of each player's turn. If it wakes up after the other players turn, BEFORE yours then it would act normal on your turn.
Source: WotC Chat (2000-05-11)
Gameplay » Deck
Can I have an English Dark Blastoise on the side while having a Water Energy with Dark Blastoise written on it in my deck and play it in a tournament?
No, you'll have to use the Dark Blastoise.
Source: WotC Chat (2000-05-04)
Gameplay » Special Conditions
In the rules it states that when a Pokémon evolves it becomes free of Poison, Sleep, Confusion, Paralysis, or anything else that may be the result of an attack. Does this mean that damage is also taken off of it when it evolves?
No.
Source: WotC Chat (2000-04-27)
Gameplay » Special Conditions
If an opponent already has Nidoking's Toxic double Poison, then next turn I use a "normal Poison" attack, does the opponent retain Toxic's double Poison condition or does it now become a single Poison condition?
It would gain a single Poison effect (the new effect replaces the old one).
Source: WotC Chat (2000-04-27)
Gameplay » Bench
Dark Dragonite's Pokémon Power does not have the "you cannot use this Power if your bench is already full" text like most other Bench-building powers and attacks do. Does this mean that by using Dark Dragonite you can bypass the normal five-Pokémon limit to your bench?
C'mon. That's silly. There isn't room to put the reminder text on every single card. The rule is the bench can only have 5 max (EVER).
Source: WotC Chat (2000-04-27)
Gameplay » Evolving/Devolving
Dark Pokémon evolve from Basic Pokémon. Once you evolve a Basic Pokémon into a Dark Stage 1 Pokémon, it CANNOT evolve into a non-Dark Stage 2 Pokémon, only a Dark Stage 2. "Once you walk down the Dark Path, forever will it dominate your destiny" - Yoda the non-Pokémon.
Source: WotC Chat (2000-04-13)