Pokémon FireRed and LeafGreen/Route 22

'These routes are a good place to collect more Pokémon. Route #2 (shown below) is full of Pidgey and Rattata, along with a specimen or two that are rarely found in this area. Remember to weaken a Pokémon in battle before using a Poké Ball on it, or else it will be able to break free. The first time you come through Route #2, head into Viridian Forest to continue your journey.'

Gary Awaits
If you want some quick EXP (and 144), you can challenge your rival in Route #22 by heading west towards the pond. But don't do it until you have a few strong Pokémon! You may want to wait until after Viridian Forest... Or skip it all together.