The 1st Edition cards could be used for the Pokmon Trading Card Game, but as noted earlier, even in 1999, kids were aware of the value of the Charizard card and most were opening booster packs to find this card rather than use the cards for the game
You have a pretty good chance of getting more than 3 mana's worth of value out of Brimaz
Slam some big black instants and watch the world burn, Dictate of the Twin Gods, City on Fire, and Kaervek the Merciless really make it hurt
Honorable Mentions Several cards from both sets came close to cracking the top 10 and deserve a mention for their collector appeal and steady secondary market performance
Bloodbraid Marauder Bloodbraid Marauder is a bit of an odd one
The set's design draws directly on the Team Rocket expansion (1997 in Japan, 2000 in English) the original set that introduced Owner's Pokemon as a mechanic and established the villain-faction angle in the TCG