When Dimension Valley is in play, if Mew EX uses its "Versatile" Ability to copy an attack from another Pokemon, will the attack's Energy cost be reduced by (C)?
If I play Lysandre's Trump Card and I have a Lysandre's Trump Card from a previous turn in the Discard pile does that card get shuffled back into my deck?
No, the wording on Lysandre's Trump Card that says "except for Lysandre's Trump Card" is referring to all Lysandre's Trump Cards in the Discard pile.
Source:
Phantom Forces FAQ (2014-11-13), TPCi Rules Team (2014-11-13)
I am playing a Robo Substitute from my hand to my Bench, but my opponent used Venomoth's "Dizzying Wind" attack last turn. Do I have to flip to play it?
Yes, Robo Substitute is a Trainer card when it is played.
Source:
Phantom Forces FAQ (2014-11-13), TPCi Rules Team (2014-11-13)
What's the proper way to play a Trainer like Ultra Ball?
When playing a Trainer you first put it onto the playing field (not directly into the Discard Pile). Then you do what the card says, such as discarding two cards (those go into the Discard Pile right away), searching your Deck, showing the selected Pokemon to your opponent before putting it directly into your hand, shuffling your Deck, etc. Finally, after everything is done, put the Trainer card into the Discard Pile.