Hiya ^-^
I gave both my Stakataka away a while ago but I do have a Naganadel I soft reset so it could be a BR mon (took less than 30 tries <3)
You can get a Poiple in the ultra megalopolis once you beat Necrozma though, and you can soft reset it to be shiny (It looks like a bee

)
The Naganadel is my precious purple bee though but I would be ok with parting with it
(if you happen to have a HA luxury ball Fenekin that would be amazing)
Also, I can give you a Guzzlord to put into GTS for a Stakataka, people seem to love the chunky thing for some reason (it really isn't that hard to get though)