Does the effect of Iris occur when you play it or when you attack?
Iris' effect looks at the game state at the time of the attack, not at the time when you play it.
Source: TPCi Rules Team (2014-01-02), TPCi Rules Team (2014-05-08)
Can I use Evosoda to search for a Mega Pokemon?
As long as it evolves from the Pokemon you choose, yes.
Source: XY FAQ (2014-02-06), TPCi Rules Team (2014-02-06)
If a Basic Pokemon was put into play last turn, can I use Evosoda on it twice to bring it all the way to a Stage 2?
No, you cannot. When you evolve a Pokemon it is a new Pokemon, and since it was put into play this turn you cannot use Evosoda on it until next turn.
Source: XY FAQ (2014-02-06), TPCi Rules Team (2014-02-06)
Can you use Devolution Spray or Golurk's "Devolution Punch" attack against a Mega Pokemon, and if so what happens to the Mega Pokemon?
Mega Pokemon are evolved Pokemon, so the Mega Pokemon card is removed, but the underlying Pokemon and all other cards attached stay in play (unless the Pokemon is KO'd, of course).
Source: XY FAQ (2014-02-06), TPCi Rules Team (2014-02-06)
When using Max Revive, if I choose Blastoise can I put Wartortle & Squirtle into my deck too?
No, you only get to choose one Pokemon card, not an entire evolution line.
Source: XY FAQ (2014-02-06), TPCi Rules Team (2014-02-06)
What happens if you play Super Potion for a Pokemon that doesn't have any energy cards attached to it?
You still remove 60 damage (or as much as you can), but that's all.
Source: XY FAQ (2014-02-06), TPCi Rules Team (2014-02-06)
While there are no functional changes to these cards [Professor Juniper and Professor Sycamore], you may not include both of them in your deck. That is, you may have up to 4 copies of Professor Juniper or up to 4 copies of Professor Sycamore - but if you have any Professor Juniper cards in your deck, you may not put any Professor Sycamore cards in your deck, and vice versa.
Source: TPCi Announcement (2013-10-01), TPCi Rules Team (2013-11-21)
With the rule change effective November 8, 2013 about performing the coin flip before each player draws their starting hand, how does First Ticket work now?
You can still use First Ticket in your deck, but it essentially becomes ineffective since the coin flip has already taken place before the point when First Ticket can be played.
Source: TPCi Rules Team (2013-11-21)
For Cedric Juniper, can the opponent look at any face up cards around them to figure out the height of a Pokemon. Can he/she look at an open binder nearby?
You could look at other Pokemon that are in play but not at a binder. Just on the field, in your hand, or in the Discard Pile for either player.
Source: TPCi Rules Team (2013-11-21)
When using Cedric Juniper, my opponent asks for the height of a Pokemon in play on the field. Is it legal for him to cover that card up?
Nope.
Source: TPCi Rules Team (2013-11-21)