So, you've finally gotten past the stage of including 5 colors in a deck, (Or
like most, you've totally skipped it.) and have a decent supply of cards
built up.  So you decide, "Hmm...  I want to make a deck with Alakazam and
Jynx is it.  I'll make a psychic deck." and you put a fair amount of time
into it, and you think you have a good deck. 

However, then you run into a fatal flaw, some little thing that makes your
psychic deck a lot harder to play.  You get disgusted and decide to move back
to 2 color decks.  But don't throw away these mono-decks just yet!  All of
them have some problems no matter how you build them, and this article will
take each color one by on, discuss it's problems, then try to solve the
problems.

Psychic: 
Fatal flaw:  Sure, everyone loves playing their Mr. Mimes, Jynxs, and
Alakazams, but they seem to run into a wall somewhere most of the time.  This
horrible problem is that colorless is strong to it, and almost -everyone-
plays some.

Solution:  You're going to have to either throw in some colorless to deal
with this problem, (Which is one reason why Chancey is so popular in
psychic.) or work around it with gusts of wind to get their colored baddies
out.

Fire:
Fatal Flaw:  My personal fave.  A hard color to play right, and with no
pokemon with resistance to it, it looks solid.  The only problem is that one
of the greatest decks in existance, Rain Dance, will have the advantage
before first damage is even dealt.

Solution:  Either speed up your fire deck, (Mine can do 80 second turn and
every turn thereafter) or throw in gusts.  The problem with rain dance it
commits on energy decisions very early on, so using gusts to pull out pokemon
with no energy on them will get you a long way.

Water:
Fatal Flaw:  Everyone knows raindance, and the other big baddies like
Gyarados and Dewgong are also awesome.  But water has a very nasty problem it
must deal with before it gets its big baddies; water is very, very lacking in
good, big basic pokemon to hold off until a big pokemon can come out.

Solution:  Energy Removal fits into almost every water deck, and a majority
also fit in 1 or 2 SERs.  This should buy the time to get out the big guys. 
Also, with the release of fossil, Lapras and Articuno have given blue the big
basics to compete early on.  Expect one of these two in almost every water
deck from now on.

Fighting:
Fatal flaw:  I assume I don't even have to mention haymaker.  It is the big
bad deck type out there now, curing almost everything else.  Only flaw is
it's no secret!  Everyone knows they'll play a lot of fighting in the average
tourney, and with birds out there, as well as the favorite splash card of all
time, Scyther, fighting can have some real problems.

Solution:  I assume all fighters out there use 3 of 4 gusts because of this. 
This is the best solution to the problem.  Also, some haymaker stoppers have
become so common that haymakers come back and cure them!  Haymaker decks
everywhere are finding a new friend in ponyta.

Grass: 
Fatal Flaw:  Almost none.  Grass has no big weaknesses, has the basics it
needs, good evolutions, really everything.  The only kind of problem is that
green cards don't sem to work together very well.  You have Vileplume,
Exeggutor, Beedrill, Butterfree and others which just don't seem to click
together.  Because of so many pokemon you have to get up to level 2 before
they do much, it is also a very energy intensive color.

Solution:  The ultimate grass card, Venusaur.  His energy re-distribution can
make any green deck a killer, solving your energy problems and letting you
work any theme you have on the table.  However, without one, I think grass
will be doomed to just be the ultimate splash color.  Expect green decks to
drastically change after Muk comes in.

Lightning:
Fatal Flaw:  It could be so good.  Electabuzz, the hard to kill Raichu, and
Zapdos as a finisher, with the best (as far as I'm concerned) splash card
ever, Electrode.  However, lightning is killed by fighting.  And if you don't
think fighting is everywhere, I'd be interested in selling you real estate.

Solution:  Almost every Lightning deck there is now plays birds standard to
stop fighting.  A pair of Zapdoses are great, but a ton still trhow in
Spearow, Farfetch'ds, and Dodous just to stop fighting.  I reccomend you do
to.  If you are weak to the fastest deck out there anyway, it takes special
precautions to win.

Well, I guess that's about it.  I hope this encourages you to pull out the
old psychic deck of yours and tweak it a bit more.  It could be a killer.