In all three of the Generation II Pokémon games, both shiny Pokémon and Unown forms are determined by IV values. Because of this, it is impossible to encounter a shiny Unown in any form other than, coincidentally, I or V. Sprites for Unown's other 24 forms are present in the game's code, but they all go unused because of this programming method. Furthermore, this is the only instance of true unused shiny Pokémon in the Generation II titles, as the placeholder shiny palette for the Pokémon egg is simply a duplicate of its normal palette.

A recurring oddity in the Pokémon games is that the Gym Leader and later Elite Four member Koga, the Kanto Region's Poison-type expert, threatens to defeat his opponents with both Poison and Sleep tactics. In Red and Blue, he states:


In Gold, Silver, Crystal, and their remakes HeartGold and SoulSilver, he states:


In FireRed and LeafGreen, he states:


Despite this, the only game in the series where Koga's main team uses any Sleep-inducing moves is Yellow, where two of his Venonats have Sleep Powder. In contrast, all of Koga's teams have incorporated Poisoning moves, with some of his teams being entirely composed of Pokémon using such moves. Although possibly a mistake, this might also tie into the theme of misdirection, which would be fitting for the ninja-themed Fuchsia Gym.