(hex:80) is a glitch item in Pokémon Red and Blue. It is an unterminated name glitch item hence is applicable for Yami Shop glitch.As it is an unterminated name glitch item, it has effects associated with those items, and can be used for screen data exploits like LOL glitch, Yami Shop glitch or will usually cause the TMTRAINER effect in battle.
Using this glitch item with a 0x50 sub-tile early enough on the screen from both outside of and within a battle (the latter being possible with GameShark code 0150A0C3 or theoretically OAM DMA hijacking) may result in a freeze.
If it is used in battle without the aforementioned methods of keeping the 0x50 sub-tile stored early on the screen, it may cause the TMTRAINER effect instead.
This glitch item shares the same effect pointer as glitch item #j. (hex:00).