Sea Route 230 lists 18 Pokémon across 20 encounter methods (grass (morning, emerald in the gba slot / firered in the gba slot / leafgreen in the gba slot / ruby in the gba slot / sapphire in the gba slot), grass (morning), grass (morning, poké radar, emerald in the gba slot / firered in the gba slot / leafgreen in the gba slot / ruby in the gba slot / sapphire in the gba slot), grass (morning, poké radar), and more), between level 3 and 55. 2 of them are on no other route's wild tables in this guide: Corsola, Sealeo.
Grass (morning, Emerald in the GBA slot / FireRed in the GBA slot / LeafGreen in the GBA slot / Ruby in the GBA slot / Sapphire in the GBA slot) Lv 47-50
Grass (morning, Poké Radar, Emerald in the GBA slot / FireRed in the GBA slot / LeafGreen in the GBA slot / Ruby in the GBA slot / Sapphire in the GBA slot) Lv 47-50
Grass (night, Emerald in the GBA slot / FireRed in the GBA slot / LeafGreen in the GBA slot / Ruby in the GBA slot / Sapphire in the GBA slot) Lv 47-50
Grass (night, Poké Radar, Emerald in the GBA slot / FireRed in the GBA slot / LeafGreen in the GBA slot / Ruby in the GBA slot / Sapphire in the GBA slot) Lv 47-50
Grass (swarm, morning, Emerald in the GBA slot / FireRed in the GBA slot / LeafGreen in the GBA slot / Ruby in the GBA slot / Sapphire in the GBA slot) Lv 47-50
Grass (swarm, morning, Poké Radar, Emerald in the GBA slot / FireRed in the GBA slot / LeafGreen in the GBA slot / Ruby in the GBA slot / Sapphire in the GBA slot) Lv 47-50
Grass (swarm, night, Emerald in the GBA slot / FireRed in the GBA slot / LeafGreen in the GBA slot / Ruby in the GBA slot / Sapphire in the GBA slot) Lv 47-50
Grass (swarm, night, Poké Radar, Emerald in the GBA slot / FireRed in the GBA slot / LeafGreen in the GBA slot / Ruby in the GBA slot / Sapphire in the GBA slot) Lv 47-50