Some more bits of info. First we get some more about Roy (the boy):
- He's from the Kanto region.
- He's in possession of a mysterious Poke Ball.
Second, they wouldn't be Pokemon anime protags if they weren't visited by a Legendary on the first day of their journey, right? But instead of a Ho-Oh, it'll be a Shiny Rayquaza!
So, obviously there's some similarities between the Shiny Rayquaza and the Mystery Ball, mainly the color scheme. But I'm going to say any connection between the two is a red herring, or at least its an indirect connection (like it's not the Mystery Ball which is connected to Rayquaza but possibly a Pokemon that's inside it). Despite the similar colors, I feel the Mystery Ball's design is too ornate to be referencing Rayquaza's.
Also, the Mystery Ball's structural design looks to be a mix between a modern Poke Ball and a Hisuian Poke Ball. It has the general smooth round texture of a modern ball (aside from the lock on front of it), but at the top there looks to be a spout piece like the ones Hisuian balls have to shoot out a firework when you catch a Pokemon. This would suggest the Poke Ball is old, maybe not as old as Hisuian Balls, but by the time it was made the Poke Ball possibly hadn't fully reached its modern version which didn't require a firework spout.
And of course there's the lock on it. Only thing at the moment I can point out is the two colored bolts/gems(?) on it: red and blue. Now, before you go thinking it's a Gen I reference, I don't think so: in Japan the first Pokemon games were Red & Green. So them choosing red and blue has to mean something else, possibly something relating to our protags who are colored coded red (Roy) and blue (Liko)? I guess I should also mention red and blue do have a connection with Rayqauza, red representing Groudon and blue for Kyogre. An intended connection or another red herring? Other notable instances of red and blue I can think of is being the colors for Kalos and Galar (or at least a shade of them). All speculation at this point.
Oh, and let's not forget Roy is from Kanto. Roy's appearance is meant to call back to Red which obviously also means Ash. If the new anime takes place a few years in the future, with Ash's status as the World Champion and other accomplishments he would have done since then, maybe Ash has become a hero/legend in the Kanto region and many young trainers from Kanto now dress in a similar style to his. Would be a neat way to connect the new series to the old without needing a direct relation to Ash. Let's not make this a Star Wars thing where every major thing has to revolve around one family, let Roy and Liko be their own thing with Ash at most being an inspiration to Roy.