Quoted By:
>A Pokémon with a (barely noticeable) yellow glow will appear on very, very rare occasions in the wild (I only saw two of them, and only in the Wild Area, myself) and you'll get a bit of flavour text when the battle starts noting their apparent strength. Rather than size, though, these have much more useful aspects: yellow-glowing 'mon have at least a couple of maximum IVs - the hidden gene-like stats that dictate how good one Machop is, say, compared to another - and they have Egg Moves rather than regular ones, too.
