Golduck does not evolve
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.
In Pokémon Gold, Silver, Crystal, Ruby, Sapphire, FireRed, LeafGreen and Emerald, Exeggutor will learn Egg Boomb at Level 31 however in Diamond, Pearl, Platinum, HeartGold, SoulSilver, Black, White, Black 2 and White 2, it will learn it at Level 27.
Octillery is capable of learning Octazooka in Pokémon Gold but only at Level 25.
It doesn't. Silver Wind for Scyther is a TM Move or an Egg Move. But it's not learned naturally.
Level 58 will feraligatr learn it
I found that poliwag learns hydro pump at level 43. it's the same for gold, silver and crystal, but you'd have to keep continually stopping poliwag from evolving as it evolves into poliwhirl at level 25 and it learns hydro pump later on, at level 48.
By leveling up, Feraligatr learns Hydro Pump at different levels for each generation.In Generation II (Gold, Silver, Crystal), Feraligatr learns Hydro Pump at level 58.In Generation III (Ruby, Sapphire, Emerald, FireRed, LeafGreen), Feraligatr learns Hydro Pump at level 55.In Pokémon Diamond and Pearl, Feraligatr learns Hydro Pump at level 63.In Pokémon Platinum, HeartGold and SoulSilver, Feraligatr learns Hydro Pump at level 71.In Generation V (Black, White), Feraligatr learns Hydro Pump at level 76.
Golduck does not evolve
it will learn it at level 36
at level 35
It learns it at level 75.
Level 56.
52
Mine learned it when it hit level 31. (Heart Gold)
It can't learn Psychic.
Pysduck evolves in Golduck at level 33. It's not a gold duck though, it's blue....:)