Route 21 South — Pokémon FireRed & LeafGreen+
Every wild Pokémon here, by encounter method.
Route 21 South lists 10 Pokémon across 7 encounter methods (grass, surf, old rod, good rod, and more), between level 5 and 40.
Route 21 South in other guides
The same area in other ROM hacks on this site. Each one has its own encounter table.
Opens up at Marsh Badge — the sea routes and Cinnabar Island. 7 trainers here:
Fisherman ClaudeSwimmer♂ RolandFisherman NolanSwimmer♂ JeromeSwimmer♂ JackPsyduck Master NicoleSlowpoke Master Jill