Oddish evolves at level 21 in HeartGold.
Wooper will evolve at Level 20.
LEVEL 25
you have to trade
Level 21
Oddish evolves at level 21 in HeartGold.
Snorlax does not evolve. In gold, it is a non-evolutionary pokemon.
Bulbasaur, Ivysaur, Venusaur, Butterfree, Oddish, Gloom, Vileplume, Venonat, Venomoth, Bellsprout, Weepinbell, Victreebel, Exeggcute, Tangela, Hoppip, Skiploom, Jumpluff, and Tangrowth can all learn sleep powder when they reach a certain level.
Unowns do not evolve.
You have to have it have high happiness. It doesn't evolve at a level.
Wooper will evolve at Level 20.
LEVEL 25
Farfetch'd is a Pokemon that does not evolve.
Level 42
22
you have to trade
Level 21