Route 21 (Upper Half) — Pokémon Phoenix Red
Every wild Pokémon here, by encounter method.
Route 21 (Upper Half) lists 10 Pokémon across 5 encounter methods (grass, surf, old rod, good rod, and more), between level 5 and 36. 4 of them are on no other route's wild tables in this guide: Bulbasaur, Charmander, Squirtle, Kingdra.
Opens up at Route 21 and the Viridian Gym — Giovanni.
