Yellow MissingNo. can be seen in the wild, as it's a 50% chance he'll crash the game, or 50% chance you can capture him, where sometimes you may get side-effects like MissingNo. Learned! over and over, or an evolution (this has never happened to me yet). The Yellow MissingNo. does duplicate items in the sixth slot, before my Yellow data died (after three years of surviving), I had my HM05 in the 6th slot and after I'd captured the Yellow MissingNo. it became dulplicated and I was stuck with the item, it would never disppear form my Items when I placed it in the box. Yellow MissingNo. can been seen by normal game cartridge, GS/GG/AR, but in a ROM version you have to turn the encounter off, other wise the game will crash/emulator error.