Roaming Pokémon IV glitch
Exclusive to Ruby and Sapphire:
256x item selling price glitch | Amazing Trainers | Berry glitch | Draining hitpoints animation glitch | Evolution animation glitch | Sticky Hold glitch | Mossdeep City Skitty glitch | Truck glitch | Nightmare glitch | Mossdeep City Skitty glitch
Acro Bike instability glitches (Japanese only) | Dark red selector glitch (International only) | Excessive doll arrangement glitch (Japanese only) | Mail and Trick glitches (Japanese only) | Surf on land (Japanese only)
Exclusive to FireRed and LeafGreen:
Celadon City origin glitch | Pokédex species glitch | Roaming Pokémon Roar glitch
Exclusive to Emerald:
Battle Pike poison knockout glitch | Black curtains glitch | Mart worker glitch | Mover Vigoroth cry glitch (Japanese only)
In various or all entries:
Azurill gender glitch | Boss HP recruit glitch (Mystery Dungeon) | Decamark-specific glitches | Dewford Gym footprint glitch | Evolution move-learning glitch | Focus Punch glitch | Roaming Pokémon IV glitch | Sky Pillar glitch | Thunderbolt glitch | VBlank RNG interrupt glitch
| Bulbapedia also has an article about Roaming Pokémon IV glitch. |
The Roaming Pokémon IV glitch occurs in Pokémon Ruby and Sapphire, Pokémon FireRed and LeafGreen and was patched in Pokémon Emerald.
It causes roaming Pokémon to always have 0 IVs in the Special Attack, Special Defense, Defence and Speed stats, and a maximum 7 IVs in the Attack stat. The HP IV is unaffected by the glitch.