Where to catch, #0070
Weepinbell in Red and Green (Japan): 4 places, levels 28 to 30
Red and Green (Japan): the game page
No encounter in Red (Japan).
4 encounters by area
Places
Route 12, Route 13, Route 14 and 1 more
Other games
Also found in 11 other games
Red and BlueYellowGold and SilverCrystalXDFireRed and LeafGreenDiamond and PearlPlatinumHeartGold and SoulSilverX and YLet's Go, Pikachu and Eevee