Diglett evolves at level 26.
it evolves into dutrio
at level 26
blocking the way to diglet cave.
use lots of max repels
wake up the sleeping snorlax in front of diglet cave with the pokeflute
Arbok does not evolve.
Sandslash does not evolve.
Gyardos does not evolve.
Qwilfish does not evolve.
Ampharos does not evolve in Pokémon HeartGold.
No, Magneton cannot evolve in Pokémon HeartGold.
No, Sableye does not evolve.