@pokemonrevolution recently presented a new and likely theory for these Grey Thick stamps, which I will quote here: Grey Stamp Theory Grey stamped 1st Edition Base set cards for the most part have commonly been considered to exist because of either A) The ink was low when they were stamped B) The stamp was not pressed down with enough force to create a nice dark color
Great Unclean One makes your opponents lose life each turn with the potential to put tokens into play
Dracaufeu Brillant (Shining Charizard) Neo Destiny Shining Charizard combines two of the most powerful factors: the most popular character and the rarest card type
I claim that the Magic system, which was designed to be resonant and trope-y and archetypal, does a lot of the same good work that naming things does, and is a richer intuition pump than other popular wrong-but-usefuls like Enneagram or MBTI or chakras or the integral theory colors
Like most Pokmon cards, the value of Houndoom depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Great Encounters)
They are most likely backups or second picks for other, stronger cards, but if you need redundancy, these cards might be worth playing