The Rare Find
Although the card obtained by azdfg1 is clearly ungraded, its front does appear to be in good enough condition to attain a PSA grade of 8 or even 9. Assuming its back is undamaged, the card could easily net its owner up to $600, not accounting for the grading costs, which would be in the ballpark of $75 in this instance. Even the near-mint copies of a regular holo Dark Blastoise regularly go for hundreds of dollars.
Reddit quote is loading
The post on Reddit
The Value of Dark Blastoise #4
Finally, this particular variant of Blastoise is widely considered to be among the strongest Dark Pokemon in the entire Pokemon TCG. That's largely because of its Rocket Tackle move, which packs a decent punch and has a 50% chance of preventing all incoming damage to Dark Blastoise on the following turn. Alternatively, the Pokemon also knows Hydro Cannon, which is one of the most flexible attacks in the entire game that allows the player to do between 30 and 70 damage, depending on the amount of Energy cards attached to the creature.