It evolves at level 36.
sentret evolves at level 20 in Pokemon heartgold
Ampharos does not evolve in Pokémon HeartGold.
pidgey evolves into pidgeotto at level 18, then into pidgeot at level 36.
Level 15.
level 20
level 31
Level 30.
level 30
Level 36
Feebas does not evolve by level in Pokemon HeartGold. Feebas evolves when it levels up while it has a maximized beauty condition.
Kabuto will evolve at level 40.
Level 30