Well, I've got a savestate of it hatching, and I've fooled around with it a bit, and got it to bypass the line that was skipped (thus the dead hatch). This is what came up, after 12 Tries:
Pokémon Name: (7 random lowercase letters)
Type: Ghost/Poison
Possible Moves suggest that the pokémon is infact gastly. some moves include Night Shade, Lick, and Mean Look.
Because there is no sprite assigned to the pokémon, the display is an egg, however, when it is in the active position, no image is displayed.
The pokémon also evolves at level 33, possibly eariler, but sience it is not obtainable and the game does not breed it (no gender is assigned), and if I can get a second game pack with the hacked image, I can test the gastly theory.