Things You'll Need
Instructions
Travel to LillyCove and stand in front of the Pokemon Center. If you are unable to find Lillycove, consult the "Pokemon Emerald" world map.
Check the Pokedex to find the location of Latios. In order to fight Latios on Route 121, he must be on Route 120 while you are at the Pokemon Center. If Latios is not on route 120, use the Fly command to fly to the Pokemon Center, and then check the Pokedex for Latios again. Repeat this process until Latios is on Route 120.
Run to Route 121 and begin to walk through the grassy patches along the route. Do not run through the grassy patches; running will scare Latios away from you.
Summon Wobbuffet when you finally encounter Latios.
Attack Latios with Wobbuffet's Mirror Coat ability, which inflicts twice as much damage as Latio's Luster Purge and Psychic abilities. Once Latios' HP has reached yellow or red levels, stop attacking him.
Heal Wobbufet with Hyper potions whenever his HP begins to run low.
Throw Timer Balls at Latios until you catch him. The Timer Ball's catch rate increases with each passing turn.