How rare is this Pikachu error/misprint card?

[quuador]

As mentioned by @thymeee , your misprint is indeed the Ghost stamp error. The one where it’s grey instead of black you’ve mentioned is a Grey stamp error.

Some more information about ALL Base Set Pikachu variations can be found in this article I wrote: Base Pikachu artwork card variations.

To quote the relevant part for your Ghost stamp Pikachu:

@quuador

**English Ghost/Phantom “E ITION” 1st edition misprint:

**
In this misprint, the 1st edition letters are only partially printed, leaving out the “1st” part, and the “D” in “EDITION”. Also, unlike the regular black 1st edition symbol, the letters are hollow and only have the outline printed. Despite being a pretty strange misprint with these charismatics mentioned above, the Ghost/Phantom 1st edition misprint isn’t a one-of-a-kind occurrence and is actually pretty well-known.
Although it was never confirmed, these “E ITION” markings of the Base Ghost/Phantom Pikachu might have been added during the printing process as indication, so the 1st edition stamps would be properly aligned (which kinda failed in most cases). These Ghost/Phantom Pikachus slipped through the process as misprints.
With some of the 1st edition Base Set cards you’ll notice the 1st edition stamps will look almost 3D (except for the “1st” and “D”), due to misaligned 1st edition stamps. All 1st edition Red Cheeks Pikachus are probably aligned/2D, and almost all 1st edition Yellow Cheeks Pikachus are misaligned/3D. Here is a zoomed in picture of one of my 1st edition Yellow Cheeks Pikachus 1st edition stamp:

These Ghost stamped Pikachus could be found in ZAP! Shadowless Decks with a gold strip around them, which can be seen in the opening of such a Deck in this YouTube video.

Additionally, information about all 1st edition stamps can be found in another article I wrote: 1st edition stamp variations - ‘Let’s Iron It Out!’.

Again a quote of the relevant part for the Ghost stamp:

@quuador

Pikachu Ghost/Phantom stamp:

There is a misprinted Base Set Pikachu, which only has this outlined “E” and “ITION”, better known as a Ghost or Phantom stamped Pikachu. These most likely slipped through production. They might have been already printed cards, that were later used in the non-1st edition Shadowless print run, which already had these “E ITION” printing indication applied to them in an earlier step of the printing process.
Source

As for value, you’ll have to look at recent sold listings for cards in comparable condition (yours seems to be in MP/P condition), but it’s probably worth a couple hundred bucks these days.

Greetz,
Quuador