else

Gaijin. I think this knowledge was much more common on the internet a long time ago tbh.

Obtainable via memory exploits, if you want to call that hacking.

When hacking is used in context of Gameboy games then I'd normally first think of using external tools such as a gameshark to directly edit memory, rather than game glitches. I'm not sure most people would say missingno glitch is hacking but it is a memory exploit.