Just thought I'd mention this because it's been on my lately as I've been testing...
I find a grave complication between my "old school" player habits and the game as it stands now, particularly with regard to there being a "surprise" element in the game. Here's the example I came across...
I'm playing a Landorus EX/Bouffalant deck and my opponent is playing Blastoise. I run 4 DCE in my deck, which works very well with Bouffalant. The problem, though, is that I tend to hold the DCEs in my hand a lot, with the anticipation that I'll surprise my opponent and throw him/her offguard. In the back of my mind, I'm also vaguely afraid of an Enhanced Hammer dropping the field and now I'm set back a couple of turns. Couple of things though...
1. I'm setting myself up to lose a DCE attachment by my opponent playing an N. I now just denied myself a chance to play a card that would greatly be to my benefit.
2. Blastoise decks do not run Enhanced Hammer. I should know this from experience, so why be vaguely afraid of something that will never be a factor?
3. I'm playing with an older style of play in mind. During the "ex series" days, I often used decks that would greatly disrupt my opponent in various ways. It's why I fell in love with MetaNite, a deck that could easily wipe Pidgeots out of the game entirely. Add that element to a well-timed Rocket's Admin. (today's N), and you get a single turn that decides the outcome of the game. The game as it is today, however, allows for surprises in the form of OHKO's. Taking out an EX is a BIG DEAL. But for some reason, I still want to hold on to my DCE, as if playing it in conjunction with the OHKO is the ideal play. In many cases, it's not.
... just some thoughts about how old playstyle can effect the moves you make in today's format.