What is required for 100% completing Pokémon Go?

I've been having a few nostalgic memories involving the Pokémon franchise lately. Said memories include The Pokémon Black & White Anime that i used to watch everyday on CN, the movies that also used to air on CN and all the Pokémon Go content i used to watch back when it was at peak popularity, among other stuff. I've recently started playing Pokémon Go for the first time in years thanks to the nostalgia for all the content i used to watch of it, and since i'm a completionist, i've been wanting to 100% complete Pokémon Go.

So i'd like to ask: What are the 100% completion requirements for Pokémon Go?