Well, everyone seems to "know" that the pokemon are THE most important part
of any deck.  However, it often appears that people just DON'T put a lot of
thought or strategy into their choice of pokemon.  I'm not talkiing about
"good" pokemon vs. "bad" pokemon (every pokemon has some sort of use), but
rather poor combinations, ratios, or strategies behind their choices.  I'm
not making this up, if you look at the killer decks section, you're sure to
see more singles than the average Digimon deck.  There are also decks using
all sorts of assorted pokemon, like Dittos, Jigglypuffs, etc. that are just
thrown into a deck for absolutely no reason.  Additionally, there are decks
that contain more Stage 2's than come in the whole Team Rocket expansion set.
 Claims of "It works for me" or "This pokemon has helped me win tournaments a
few times" just don't cut it when the choices are this bizarre. I'm going to
cover a few different topics, including:  How many pokemon, What ratios to
use, What kind of pokemon to use, and How to make room for the right pokemon.
   
    How Many Pokemon to Use:

    This depends on the deck.  Basically, it goes like this:  If your pokemon
are all basics, then you should use somewhere between 12 and 15 pokemon. 
This gives you plenty of room for necessary trainers but gives you enough
basics to prevent mulliganing.  If you use a deck with evoltutions, 14-18
pokemon works nicely, given that you need more room for Stage 1's or 2's, but
still keep up a reasonable number of basics (mulliganing again).  For a stall
deck (or any other low-energy deck) 16-20 pokemon is reasonable, as it leaves
enough room for the valuable trainers that make up so much of a deck, and
keeps your important pokemon in play.  Finally, for a Hayfever trainerless
deck, pokemon should make up approximately 23-25 of the 60 cards, and should
have attacks/powers that make up for the loss of trainers.

    Pokemon Ratios:

    Although this also depends on the deck, there are more solid rules for
this.  For evolutions, Evolutionary pyramids are your best bet, unless you
are playing Breeder.
    Good pyramids look like this:
            B - S1 - S2
            4   3     
            3   2
            4   3     2
            4   1     3  + 3 Pkmn Breeder

Breeders should only be played if it is utmost importance that the Stage 2
come out early (like a Turbo Blastoise), that you have multiples of a Stage 2
(e.g. Curse Damage Manipulation decks, Nidocide decks), or that a Stage 1 is
totally worthless (e.g. Fling decks, Dark Charizard Decks).  Otherwise, using
a normal 4-3-2 pyramid is just fine. 
    In addition to evolution ratios, there are certain ratios that are
required when putting all your pokemon together.  You should try to only use
1 evolution family if you use a Stage 2, or at maximum, 2 if you use a Stage
1.  Occasionally, Stage 1's can be mixed with Stage 2's, but the the Stage
1's should be run 3-2, and should be vital to the strategy of the deck. 

    What kind of pokemon to use:

    Pokemon should consist of no more than 2 color-types, with an exception
made for pokemon with entirely colorless attacks and for decks like
potpourri, a deck type that SHOULD NOT be tried by those without a lot of
experience.  
    There are also 3 different styles of pokemon.  There are quick attackers
(AKA Haymakers), there are big, developement-intensive pokemon, and there are
stalling pokemon.  Haymakers CAN make up an entire deck, as can stallers, but
normally, both are integrated into a deck focused of a developed monster. 
Normally, a deck will have 2-3 stalling pokemon (like Kangaskhan, Lapras,
Lickitung, Chansey, etc.), 4 Haymaker pokemon (Hitmonchan, F Magmar,
Electabuzz, Scyther, MP Mewtwo, etc.) and one or two 3-2 or 4-3 evolution
lines.  Sometimes BBB's (big, bad basics - Zapdos, Articuno, etc.) will fit
in somewhere, as might a 4-3-2 or turbo evolution line (turbo means 4-1-3,
with at least 3 breeders).  However, these rules are meant to be broken, as
some decks just don't adhere to these ratios.  Here, you need to experiment a
little and figure out the exact amount for your deck.

    How to make room for the right pokemon:

    It's fine to say that one needs to limit the number and types of pokemon,
but doing it can be kind of tough.  Really, it relies on centralizing your
strategy and eliminating all pokemon that don't fit it.  To do this, I'm
going to use an example.  Here's the deck:

23 Pokemon:
4 Dratini (B)
3 Dragonair (B)
2 Dragonite (Pr.)
4 Psyduck (F)
3 Golduck (F)
4 Eevee (R)
3 Dark Vaporeon

15 Trainers:
4 Bill
2 Oak
3 E.R.
3 P.C. Search
3 G.O.W.

18 Water Energy
4 D.C.E.

Not a bad deck, but it has a little trouble with the number of pokemon and
the focus.  As one can guess, this deck is centered around removing energy
from the opponent's pokemon.  However, the trainers are rather slim, and the
pokemon are simply to numerous.  We're going to cut the pokemon down a
little, and make this deck a little faster and more versatile, and also make
room for more trainers.  First,  Dragonite does nothing to fit the strategy
and isn't a great pokemon anyway.  We're going to can the Dragonite, leaving
2 spaces.  We still have three 4-3 evolutions, which is way too much. 
Dragonair stays because it has high HP, another reasonable attack, and a good
resistance, so that leaves Golduck and Dk. Vaporeon.  One of these evolutions
has to be canned, so I'm going to lose Dk. Vaporeon, since it has lower HP
and Eevee isn't that good.  We'll throw in 2 or 3 Lapras as a staller and a
haymaker component (Water Gun is reasonable, and Confuse Ray is good too, not
to mention 80 HP).  We'll drop the Dragonair line to 3-2 as it is a little
slower than Golduck.  The final number of pokemon comes up to 14 or 15
pokemon, a perfectly fine total. 

    In other words, get rid of the weaker pokemon, the pokemon that have no
business in the deck you're using (for instance, a grass deck with both
Venusaur and Muk), and put then put in whatever pokemon you lack.  Sometimes
you'll find a basic or stage 1 that has the same attack as a higher stage
(e.g. Kangaskhan's Comet Punch is nearly identical to Dragonite's Slam), and
can replace a bulky evolutionary line with a few streamlined basics. 
Sometimes you can reduce an evolution to 3-2 that was previously 4-3.  Using
one or more of these tactics, you can successfully limit the number of your
pokemon and make your deck much more efficient.

    Well, that's about all for now, as if you are really interested in
reading any more.  Hope this is of help to someone out there.

                                                    -Foss, the Magikarp
Trainer
                                                        AKA FossilMagikarp
                            email and positive comments to: Edestus360@aol.com