Pokémon Sun and Moon players can actually capture Salamence early in the game. In fact, they can get one on the first island where their Pokémon journeys will begin, which is Melemele Island.
With a bit of luck and a lot of patience, anyone can successfully catch a level 10 Salamence as soon as they start their adventure, but it's not exactly as easy as one-two-three.
That said, here are all the steps and preparations you have to take to do this without a hitch.
How To Capture Salamence Early
Step 2: Get your hands on an Adrenaline Orb, an item that'll increase the chances of a wild Pokémon to call for help. However, you have to complete Mallow's Trial on the second island Akala Island first before you can purchase one.
Once that's done, you can buy it in Hau'oli City, Heahea City, Konikoni City, Malie City, Paniola Town, Pokémon League, Royal Avenue, Seafolk Village and Tapu Village.
Note: This isn't exactly necessary, but it'll make things a whole deal easier.
Step 3: Stock up on Revives, healing items such as Potions and Super Potions and items that replenish PP such as Berries, Ethers and Elixirs.
Step 4: Head to Route 3 on Melemele Island. There, you'll find a wooden bridge. Cross it and look for the first patch of grass to your right, where there's a 1 percent chance to encounter a Bagon.
Remember, don't go to the grassy area to your right BEFORE the bridge.
Step 5: When you finally come across a Bagon, use Adrenaline Orb right away and get its health low so that it'll call for help.
Basically, what you're going to do here is to make the wild Pokémon keep calling for help over and over again until a Salamence comes to the rescue, which is similar to the method on how to catch shiny Pokémon easily.
Bonus Pro Tip: Find a Pokémon that can learn False Swipe, a move that will keep you from accidentally knocking out the enemy. Alternatively, you can use your free Munchlax via Mystery Gift for this, as it has a similar ability called Hold Back.
That's pretty much it. As mentioned earlier, you're going to need a lot of patience to make this work, but as everyone might agree, getting a Salamence early in Pokémon Sun and Moon is worth the trouble.
With all said and done, don't forget to take a look at our other Pokémon Sun and Moon guides on how to evolve Eevee into Sylveon, Leafeon, Glaceon and more; how to get all the legendaries and Ultra Beasts; how to catch rare Pokémon using the Island Scan feature; and where to find Eevee, Pikachu and Growlithe.