Can you have 4 Electivire and 4 Electivire Lv.X in the same deck?
No, Lv.X Pokemon are considered the same as other pokemon with the same name. You may only have a maximum of 4 combined in your deck (i.e. 3 Electivire, 1 Electivire Lv.X).
Source: PUI Rules Team (2008-09-25)
Can I have 4 Deoxys Attack Forme and 4 Deoxys Speed Forme in my deck?
Yes, the "Forme" is part of the name, so you can have 4 of each.
Source: PUI Rules Team (2008-08-07)
If an action is *optional* (e.g., playing a Trainer, attaching an Energy, attacking your opponent's Pokémon, etc.), and you forget to take that action, you may ask your opponent for permission to take that action. For example, if you attach a Grass Energy to your Pokémon, and you wanted to attach a Fire Energy, you may ask your opponent's permission to take back the Grass Energy and attach the Fire energy instead. If he or she says no, you're stuck with the Grass Energy.
Source: Organized Play Announcement (2007-03-14)
If an action is mandatory (e.g., draw a card at the beginning of your turn, take a prize for knocking out a Pokémon, place damage counters for an attack, etc.), and you forget to take that action, you do not need your opponent's permission to do it. However, you should immediately call a judge so that things don't get muddled.
Source: Organized Play Announcement (2007-03-14)
My opponent MUST put their basic down first before they draw 1 card for my mulligan, right? Say my opponent draws a better choice starter Pokémon when I mulligan, are they allowed to switch it out with another from their hand?
They must place their active Pokémon and their prizes before optionally drawing a card for the mulligan. Once placed, the active cannot be changed during setup; but you are allowed to add a new Pokémon to your bench, if there is room.
Source: PUI Rules Team (2005-06-16), PUI Rules Team (2006-02-09), PUI Rules Team (2006-07-27)
Before starting the game, Player-A has a Basic Pokémon but Player-B does not. On Player-A's draw 1 card for mulligan, say they draw a better choice for starting Pokémon; are they allowed to switch it out with the one they chose to be their 1st active before the mulligan? And if they choose to switch, must it stay on the field and not allowed to be put back into hand?
Player A continues his or her setup and can choose to draw an extra card after setting aside his or her Prize cards. Once placed, the active cannot be changed during setup, but a mulligan card can be placed onto the bench.
Source: PUI Rules Team (2005-05-05), PUI Rules Team (2006-02-09)
In a sanctioned Tournament, does the player have to show his hand in the event they have no Basics at the start of the game? The Floor Rules don't explicitly say that they have to.
Yes, you still reveal your hand before you shuffle it back into your deck. The rules from the rulebook still apply unless specifically stated otherwise.
Source: PUI Rules Team (2003-10-16), PUI Rules Team (2006-01-26)
Is it required to have a Basic Pokémon in your deck? For example, could I make a deck with just the fossils and no other Basic Pokémon in it?
Starting with EX:Delta Species, there is now a requirement to have at least 1 Basic Pokémon in a deck in order to be considered a legal deck.
Source: PUI Rules Team (2006-01-12)
Could I use a Poké-POWER, Poké-BODY, Attack, or Trainer to search through my deck for a particular card if I already know that card is not in my deck (i.e. using Energy Search if you know there are no basic Energy left in the deck due to previous unsuccessful searches)?
Yes you may, but if done repeatedly a judge may evaluate whether it's being used legitimately or merely as a stalling tactic.
Source: PUI Rules Team (2005-12-08)
I have Hidden Legends Electrode and use "Mass Destruction" to knock out Electode and the defending Pokémon. If I have only one prize left and my opponent has more, but I have no bench and my opponent has a bench, do I still win?
No, in this situation it would go to Sudden Death. However, if the opponent did not have any Pokémon on their bench, the Electrode player would have two win conditions vs. one, and would therefore win the game.
Source: PUI Rules Team (2005-03-10)