There are tons of Pokemon card out there, and there is a huge lot that
are underrated. I only state a few, but there are many more out there.

Beedrill - While it only has an average (or below average) Stage 2 HP,
its attacks are pure killer! Poison Sting does 40 with p poison for only
THREE GRASS. There is a good possibility for 50 damage. Twineedle would
work well if you're playing a mono deck, or if you're loaded on DCE.

Jynx - Many have realized Jynx's power, but not enough people have.
Doubleslap is average, but the 20 potential is something to feel good
about. Meditate is a pure killer attack, Gust of Wind + Jynx is
extremely powerful.

Kadabra - While looking at the almighty Alakazam, some still
(unfortunately) overlook Kadabra's PP Recover and 1PP Super Psy 50 which
is a ridiculously good attack

e-mail me at bbni@yahoo.com
if you have more underrated cards, please feel free to send them to me
:)
Happy Holidays!