Twist Mountain — Pokémon Black & White
Every wild Pokémon here, by encounter method.
Twist Mountain lists 6 Pokémon across 4 encounter methods (grass (autumn / spring), grass (summer), grass (winter), dust cloud), between level 28 and 31. 2 of them are on no other route's wild tables in this guide: Gurdurr, Cryogonal.
Twist Mountain in the official games
The original game's table for this area: