If you want to see the relevant pictures, look at it's Pokédex entry on bulbapedia.
So, this Pokémon has a weird entry. I don't know what causes it, but whenever it occurs, a message box repeatedly shows " p learned MASTER BALL". (It may vary by item; I caught it with a master ball).
Eventually, it displays " p is trying to learn". Then, the game freezes. While this is happening, weird glitch music plays.
What's especially odd is that this effect occurs nearly every time. (Occasionally, the game crashes).
Additionally, I've had this effect occur in REVERSE with female symbol: " . is trying to learn" repeatedly, followed by " . learned [Something, I forgot…]", all with very similar glitch music.
Has anyone else seen this? I have no idea if it is just a side effect of TheZZAZZGlitch's debug rom, but I doubt it is so.