This is the kind of limited-ticket event I'm picturing!

There's no way TPC
wouldn't tie an entire theme park land into one of their big, yearly (or bi-yearly) events. Even if it's not marketed internationally, the national/regional draw would be huge. Just imagine the ticket, hotel, and merch sales!
But, seriously, hosting a yearly event like this makes a lot of sense for Universal & Nintendo/TPC. Pokemon is such a kinetic franchise, and battling other trainers is a big part of that. It's part of why Pokemon Go exploded in 2016--you could catch Pokemon anywhere and engage in battles right on your phone. It would be difficult to bring that trainer vs. trainer energy with a ride, but regional/national events like this would definitely add great energy. TPC has gotten great at presenting these competitions in a very crowd-pleasing way. It's not just a couple of kids sitting at a folding table playing while people watch a dodgy, overhead stream from their chairs--these battles are big events put up on large screens that everyone can stop and watch, even if they aren't in the event room itself.
Adults and families will absolutely flock to this land, and "Pokemon Days"would be a huge win. Probably a logistical nightmare, but the pros outweigh the cons here. And a state-of-the-art theme park could offer so many more experiences on top of what Worlds already offers during their event. Even if TPC didn't tie it into their tournament schedule (I'm not up on the current guest numbers Worlds brings, but its held in large convention centers for a reason), hosting something in the park in February/March when they usually do their big "Pokemon Presents" for the year would be huge.
And, again, the sales potential!