level 1
Sceptile doesn't evolve. It's already the final stage of evolution.
Treeko evolves into Grovyle at level 16, then Grovyle evolves into Sceptile at level 36.
For Ruby, Sapphire, and Emerald, it can't. For Diamond, Pearl, and Platinum, it can't.
It is not found in the wild, you need to either trade from Ruby/Sapphire/or an other emerald, or choose Treecko as your starter pokemon, and evolve it twice, level 16 for a grovyle and level 36 for the sceptile.
Sceptile
You can´t learn bullet seed by leveling up. But you can get the tm for bullet seed at route 104 near the flower shop from a guy. Sunflora is the only pokemon that can learn bullet seed by leveling up.
It is your Starter only in Pokemon Emerald, Ruby & Sapphire Treecko evolves into Grovyle at level 16 Grovyle evolves into Sceptile at level 36
Inuit
level 75
Level 25.
level 45
Oddish learns Sweet Scent at Level 7 in Pokémon Ruby.