Where to catch, #0087
Dewgong in Diamond and Pearl: 2 places, levels 40 to 55
2 encounters by area
Places
Sea Route 226 and Sea Route 230
Other games
Also found in 10 other games
Red and Green (Japan)Red and BlueYellowFireRed and LeafGreenPlatinumHeartGold and SoulSilverBlack and WhiteBlack 2 and White 2X and YLet's Go, Pikachu and Eevee