Two many times I have seen players of the pokemon card game (both novice
and experienced tournament players) automatically fall into the niche of
constructing decks made of only two colors or one specific color and colorless.
Certainly I strongly support the idea that having more than two types of energy
in your deck is a bad idea (in most cases), but just because you're only using
two types of energy doesn't mean you have to be limited in the pokemon you use.
One combination that I have adopted, and found highly successful, is throwing
in Charmanders, Charmeleons, and Charizards in any type of deck. The reason
that this combination of cards works in any deck is simple. All evolutions of
Charmander have one attack that requires only colorless energy. Charmander has
"scratch." Charmeleon has "slash." And because of Charizards pokemon power it
doesn't matter what energy you use. Especially for decks based primarily on
large numbers of fairly weak pokemon (generally plant) a couple of cards that
have high hit points and deal serious damage are an invaluable asset. 
    But while the evolutions of Charmander are the best (in my opinion) when
used in this manner, there are other cards that can be used in this manner:
Ponyta (and its evolved form, Rapidash, especially since it also has no retreat
cost) and Paras and its evolution Parasect Jungle expansion.
    I hope that these tips have been helpful to those coolest of CCG players:
Pokemon Masters!!!!!
You can reach me (Johnny) at
<mailto:johnny2001@earthlink.net>johnny2001@earthlink.net