Hi @xlittleflowerfawnx !
I’m assuming you’re playing Ultra Sun or Ultra Moon? I haven’t played much of the new games yet, but I completed the Alolan Pokedex in Pokemon Moon last year. The best advice I can give is to stay persistent, and team up with a friend or two. (at least one with the game you don’t have). If you and a friend have opposite games, it’s possible to complete the Pokedex without going to the GTS (except for maybe the starter Pokemon if you don’t have them).
Start by exploring the islands and catching all the Pokemon you can that you don’t currently have, or work on finding all the Pokemon obtainable on one island, while a friend works on another island. Some are hard to find, so Google is your friend when it comes to finding them all. It can be very time consuming, as some can only be found in special conditions like SOS battles, and others just have a very low chance of appearing.
The next part of completing the Pokedex is evolving to get all the Pokemon that can’t just be found in the wild. With your friend(s), assign who will evolve which Pokemon. Start with the ones that evolve by levelling up, and by trading, they’re the easiest. (remember some only evolve during the day/night/if they know a specific move, etc)
Touch trading is key with filling some dex entries. If your friend has a Pokemon you don’t, and vice versa, trade with them and trade back. I did this a lot when filling my dex. There are some Pokemon that are so hard to obtain more than one of legally, that you just kinda have to accept that you wont have one yourself for a while. For example, Alolan Ninetails and Sandslash can only be obtained by using Ice Stones, and you can only find one stone per game (unless you’re lucky and get one in Poke Pelago). So evolve the one you have, get your friend to evolve the other, and trade and trade back.
Then it’s just the legendary Pokemon. Cosmog can be obtained post-game, and Cosmoem will evolve into either Lunala or Solgaleo depending on what game it reaches level 53 in. And just trade the ultra beasts with your friends.
It’s a bit annoying and time consuming, but stick with it, the sense of accomplishment when you’re done is really awesome. Plus there’s the shiny charm which is nice too :D
If you’re looking to complete the national dex and want to avoid the GTS and illegitimate Pokemon, then you’ll need to move Pokemon up from previous games. Also, keep up to date on official distribution events, sometimes you can use codes to download Pokemon via mystery gift.
Thanks for the question! Good luck!
