Thanks for the information, i'm very happy! I don't want to sound full of myself, but i did get all the legendaries already by trading away shinies that i got through wonder trade and chaining in the GTS. So far, i have 380 of the pokemon on the Alola Dex, i only need a few stray common ones.
02/08/2020 Update - I've completed my Alola Dex and have the shiny Charm. I'll write down how i did it for all future people looking at this question.
1 - Do Wonder Trade until you get a shiny or a legendary.
2 - If you don't want it, trade it away for something of equal value.
3 - Repeat the process.
4 - When you get bored, look up where some rare pokemon are and hunt them for some change.
5 - Go in the Poke Pelago and plant berries to Relax.
6 - Repeat step 1 and 2.
7 - Listen to some Music for Motivation
8 - The final but hardest part. Have faith that someone in the world is going to give what you need. There may be times where it seems impossible to get a certain Pokemon.
9 - Believe in Yourself. You are the only one who will open the path to happiness.