Yeah, I only just finished it. I recently couldn't play Xenoblade, so I focused the time on Pokemon instead.
So, my party when I beat the game and then a few thoughts on the changes to the story in Ultra.
My party is fairly similar to the run for Pokemon Moon, though I made a couple of changes. To be honest, Butterfree didn't play as big of a role as I hoped, but it still was great for near-100% Sleep.
And as levels show, Magnezone really is useful for so many situations due to his resistance.
As for the story, most of the changes were good or okay in my opinion. Matsurika (hippie artist) finally got proper screentime and her own trial. And she also had a few funny scenes, like when she did her Z-pose behind the tree only to be found by the camera.
Your rival was also the final opponent for the Pokemon League.
And so on. Good changes.
The only problem I had was with Lusamine. She keeps some of her insanity traits from the previous game, but her motive changed to finding her husband and her whole opening another world thing changed to her doing so because she thought she was strong enough.
Because of this, I felt a mismatch. Her character became half-hearted because she couldn't be 100% bad guy... and frankly, her good guy part wasn't interesting. Heck, she was so lame because she goes into the Ultra Hole to fight the big boss only to be spit back out like a toy. And she didn't really even do anything. The big baddy wasn't so bad itself, by the way. Just... everything about Lusamine, really.
Her old crazy octopus-fusion gig was definitely better.