Default-form artwork 
Generation 4 · Pokédex profile
Sea Slug Pokémon
Pokédex entry
It oozes a purple fluid to deter enemies. While harmless, the fluid is awfully sticky. Apparently, there are more West Sea Shellos now than there were in the past.
Battle data
Pokédex entry
It oozes a purple fluid to deter enemies. While harmless, the fluid is awfully sticky. Apparently, there are more West Sea Shellos now than there were in the past.
Battle data
Pokédex entry
It's capable of spending a limited amount of time on land until their skin dries out. One theory suggests that living in cold seas causes Shellos to take on this form.
Battle data
Conditional evolutions can require additional game-specific prerequisites beyond the displayed method.
| Method | Location | Level | Evidence |
|---|---|---|---|
| Fishing (rare)Form: Shellos East | Route 132 | Old Rod: Lv. 5–10 · Good Rod: Lv. 10–30 · Super Rod: Lv. 25–45 | Source-indexed, not individually verified |
| Surfing (rare)Form: Shellos East | Route 131 | Lv. 5–35 | Source-indexed, not individually verified |
| Surfing (rare)Form: Shellos West | Route 22 | Lv. 20–25 | Source-indexed, not individually verified |
Rare grass and Surfing encounters inherit the first native slot's level range. Supplemental fishing follows each rod's native slots. These ranges exclude Lure effects and randomizer replacements; eligibility restrictions still apply.
Data source: configured Grand Anthology Gen 1–9 species, forms and abilities. The website uses frame-cropped copies of the game's existing Pokémon sprites, which remain franchise/artist-owned assets. Some alternate forms use labeled default-form artwork when their individual sprite is unavailable. See acknowledgments for credits.