S t a p l e s
What are the format's current "staples" -- that is a tough question.
Awhile back, I was trying to put together a good "skeleton" trainer group. A group of T/S/S that you could drop into any deck. It just wasn't appropriate.
Bebe's Search and Roseanne's Research -- highly used
Luxury Ball -- hard to see any reason not to play (at least) one in your deck
Uxie / Claydol -- great for draw power, but don't use 'em in a Scizor deck
GE Pachirisu -- Underused, and would not be considered a staple, but arguably "fits" in any deck (one energy to Call for Family and get 3 Pokemon!)
Other Staples -
"Draw" Supporters like Professor Oak's Visit, Underground Expidition
"Refresh" Supporters like Cynthia's Feelings and Looker's Investigation
When I make a deck, I choose my pokemon (main hitters, starters, draw, any "techs", etc) ----- I then figure out how many energy makes sense - I usually go with 12'ish... (I guess the World Champion Beedrill deck only had 6!)
I then look over a list of Trainers/Supporters/Stadiums to see which ones will best compliment my main strategy. I use this list ---
http://www.pokebeach.com/forums/showthread.php?tid=59177
So, my answer to your question is "wow, that's a tough question"