I would like to start off by saying that I've played in 5+ tournaments that 
contained more than 40 people each.  My brother and I have made it to the 
final 8 every time.  I have seen sooooo many haymaker decks ruined by playing 
certain cards that do not help the deck's focus.  There are also certain 
cards that should be in every haymaker deck....

Gust of Wind: I know it's a common, but it has won me soooo many games.  
bring out their weak pokemon, and bash it in the head.

Bills and Professor Oaks: I've seen too many decks not put enough of these 
great cards in them.  For a fast haymaker to work, you need to draw a lot of 
cards.  In my opinion, every deck should contain 4 Bills and 3 Oaks.  This 
provides the deck with speed.

Farfetch'd: No matter what kind of Haymaker you play, (fighting-electric, 
fighting-fire, etc...) farfetch'd should be in it.  With fighting being so 
prevelent right now, Farfetch'd rips fighting decks to shreds with his 
resistance to fighting.

Chansey: This guy delivers a beating.  Most people use him to stall, and a 
lot of people don't know that he is STRONG!!  His double-edge often takes out 
2 pokemon before he dies.  Don't be afraid to sacrifice Chansey to take out 2 
pokemon.

Energy Removals and Super Energy Removals:  SOOOOOO important.  I can't 
stress it enough.  Recently, I had been playing 4 energy removals and 2 
Supers.  That worked well, but Now I play 4 Supers!  This seems like too 
much, but it delivers a beatdown.  The opponent can't keep energy on anything!

Scoop Up or Switch: Scoop Ups can bring back a damaged chansey or Zapdos that 
has been soaking damage.  However, Scoop ups require you to play a lot of 
energy in your deck.  Personally, I prefer switch.  Switch allows you to 
switch your active and basic pokemon.  This is especially helpful when your 
active is about to die, or when they gust of wind you.  I have had switch 
help me to not lose a single pokemon over the course of many tournament games.

I hope these suggestions help you with your haymaker decks.  I only know this 
stuff from experience in real tournaments.  When in doubt, just try stuff out 
in your deck.

haymaker18@aol.com