Where to catch, #0218
Slugma in Crystal: 3 places, levels 29 to 32
3 encounters by area
Places
Route 16, Route 17 and Route 18
Other games
Also found in 10 other games
Gold and SilverRuby and SapphireEmeraldColosseumFireRed and LeafGreenDiamond and PearlPlatinumHeartGold and SoulSilverX and YOmega Ruby and Alpha Sapphire