You answered your own question. It's Special Research, which means it has no expiration. Timed Research is not Special Research.

But Metal Gear is known for its over-the-top character writing. To my knowledge, Metroid has never been like that.

According to the overview trailer Nintendo put out a couple hours ago, characters like this are going to pop up multiple times over the course of the game. Hopefully they're not all like MacKenzie.

That's the entire point of GameShare. It's just streaming, whether to a Switch 2 or to a Switch 1. It's like DS Download Play, but better.

No. Nintendo only has 1/3rd ownership of them. Pokopia is being developed by Koei Tecmo and published in Japan by The Pokemon Company, so this is not a first-party title. It *is* being published by Nintendo outside of Japan, but Nintendo publishing doesn't disqualify it from being a Game-Key Card.

The DLC region needs to match the base game's region, so you'll need to buy or redeem the DLC through the Japanese eShop like you did with the base game. Then the UK account will be able to play the DLC without issue.

The reason it appears in English is your Switch's language setting, that's all.

"Does the Pokémon Legends ZA DLC work on all accounts on the switch as long as its a primary account that owns it?"

This is how it works for all other Switch games, so yes.

"would a Japanese DLC redeemed via a Japanese account, be playable on a UK account?"

Only if the game is Japanese.

This is how it's always looked. I think you're thinking of the Switch 2 Edition box arts.

The way I read it is 50% the $25 gift cards (so, $12.50 for a $25 gift card) and 50% off the Game Pass gift cards.

Animal Crossing: New Horizons and Mario Tennis Fever have zero bearing on Pokemon game news.

Don't forget Colosseum and XD on GameCube Classics. Still interested to hear about potential HOME support.