hi hey! sorry to leave you hanging for 21 days. i wanted to write a proper document after my move, and i did indeed start on one, but coming back to it now, i have no memory of how i planned to continue it. i'll be working on that again at some point, but for now, have some abridged notes on how the practice works for me! keep in mind that everyone's experiences and approaches are different.

1. the approach to worship is much like any other breed of paganism. i particularly focus on legendaries and mythicals, though there are other types of pagan practice that do not always focus on gods in particular and thus there are likely ways that those could be reflected here.
2. a lot of it goes the same way. tarot readings, altars and offerings, rituals. zygarde chose me before i chose it, so a lot of our "communication" - when my mind is clear enough for our connection to be stable - is just intuition. you don't even NEED to do any of the fancy magick stuff! you can just devote a part of yourself to a legendary, so to speak! hold space for them in your heart and follow them like you would any other god. i can't tell you exactly what this would look like for you, because everyone approaches that differently, but it's worth thinking on!
3. when it comes to altars, i try to use a mixture of symbolism and actual merchandise, much like other pagans may do with, for example, some symbolically colored candles and particular stones plus some actual proper representation of their god. for example, my current altar isn't actually in reflection of zygarde, because our connection is fuzzy right now! instead it's symbolic of a mythical who reached out to me when i was trying to find a connection to hold onto. i chose mostly colors that are similar to its own, as well as some items that reflect its most similar species in our world or the environment of its home region. then, in the very center, lacking any other merchandise of this legend, i've placed a pokéball crystal carving i obtained when i first started following zygarde. it's a fun little symbolic thing but also very explicitly "this is pokémon".
4. don't force it. if your connection with arceus ever feels weak, don't try to push past that. you're likely burnt out, or it has stepped back for a reason, or any other numerous reasons for that severance. know that that disconnect is most likely not permanent, and don't let it stress you. don't blame yourself for it, either - gods, legendaries, mythicals; they all are just happy to be followed and to be there to help. they don't judge you based on the quality of your offerings or the way your altar is decorated or how frequently you can do something ritual. .... er, for the most part. zygarde and floette are VERY judgmental with me but that's because we're much closer than just gods and follower. that much is obvious. :p
5. have fun with it. experiment. your approach doesn't have to reflect anyone else's. look around at pagan and witchcraft subreddits, watch videos, peruse tumblr and pinterest, whatever, but don't ever think you need to practice the same way anyone else does.

there are some poképagan blogs out there on tumblr; most are dead or post very rarely - or post about other forms of paganism as well! - but it's worth a little digging. i can't find the blog i usually turn to right now for some reason?? but if/when i do i'll reply to the tweet that links to this question with a link to said blog.

take care! may its blessings guide you, dear friend.