Honestly I can't see GameFreak do my idea of a friendly rival, it's actually kind of dark if you think about it. However thinking about the trickster tropes, it's actually kind of surprising that GameFreak has never really done a trickster/prankster for a major character in any of their games, there are some trickster-types in the manga and anime though. That's a very very common trope throughout Japanese media and I'd think it'd be perfect, and refreshing, for a innocent-looking friendly rival who has a fox-like smile that may mislead you from time to time but at the same time is still stronger than you in many ways, being more talented and tricking you a lot but is also in your face in a silent fox-like smiling way while maintaining that friendly "keep doing your best" charisma.
Just wanted to say I love this idea a ton. Doesn’t even have to be the rival - they could be a character important to the plot yet not an evil team member, rival or gym leader (could be elite four, champ or a Zinnia-type who exists purely for the story). I don’t mind who they’d be, I just love the trickster types so much.
Anyway, thinking of plot... I’m expecting at least SOME kind of connection to the parallel universes theory, for a start. Maybe it’s in postgame, maybe it’s in the story, but after the Rainbow Rocket cliffhanger in USUM I think there’s gotta be some kind of follow-up, no matter how minor. Maybe Rainbow Rocket is a division of a bigger team, or maybe they’ve just chosen Galar as their next target, I just think it’d be nice to see em either way.
Minor thing related to the parallel universes: I wouldn’t mind the URS returning considering their ability to travel to worlds willy-nilly. It’s incredibly unlikely (which is kinda sad because I love Dulse and Zossie a ton) but it’d be fun to see them back.
When it comes to evil teams, I think they’re gonna put another spin on it like with the Skull/Aether twist. I like the idea of there not being an evil team, rather just a few admins and a leader that are super powerful (which was one of my original URS speculations back in the day), but the way evil team grunts work might not fit that. I’m thinking that a team related to technology could work, considering the region’s apparent industrial influence (and I also love both steampunk and sci-fi aesthetics so yeah). I want the villain leader to be a woman like last time, and I think making them unexpected could work again too. Perhaps the character currently filling the “mentor champion” role turns on you? Or the villainous leader is the Professor? There’s a lot they can do with this one, and I can’t wait to see how they handle it!
For the rival, I guess I don’t mind much here. I like angry rivals, I like friendly rivals, as long as they’re likeable and hold some kind of role in the story I’m good.
This is probably my biggest hope but I really want Ryuki to be from Galar. He seems like the type of eccentric rock star you’d find in an urban place, and Galar has a lot of bustling cities in the northern area. Considering that you find him in USUM at the Kanto Gym Recreation, I wouldn’t be surprised if he himself is a gym leader - and considering his type preference, a late-game one.
Speaking of gym leaders, please give them and the elite four slightly more of a role. Gen VII did a good job of emulating Gen V’s Gym Leaders and made the captains and Kahunas characters with relationships you genuinely enjoy, and I’d like to see that return but with the elite four too this time. Plot relevance is optional but would be awesome.
That’s pretty much my thoughts off the top of my head. I’m really excited for Galar, and the plot will probably be fun for me regardless, but those are things I think would be cool to see!