Where to catch, #0019
Rattata in Diamond and Pearl: 2 places, levels 20 to 22
4 encounters by area
Places
Route 225 and Sea Route 226
Other games
Also found in 11 other games
Red and Green (Japan)Red and BlueYellowGold and SilverCrystalFireRed and LeafGreenPlatinumHeartGold and SoulSilverBlack 2 and White 2Ultra Sun and Ultra MoonLet's Go, Pikachu and Eevee