Things You'll Need
Instructions
Insert a copy of "Pokémon Emerald" into the Nintendo DS's GBA slot. Pokemon Diamond should be in the DS slot.
Turn on the Nintendo DS and load your saved Pokémon Diamond file. Your game will launch in "Dual-Slot" mode, which allows different types of Pokémon to appear.
Set up your battle party with Psychic, Flying, Grass, Ice or Water-type Pokémon. Flying and Fighting-types are particularly weak to these elements.
Travel to Stark Mountain or Routes 227, 215, 214, 206 or 207.
Run around the map until a wild Gligar appears. You can weaken him with ease thanks to your battle party setup and capture him in an empty Pokéball.