Alright, now you've done a bit of work to backup your claim. However, you said, "Nintendo's really the only major publisher who let's most of their studios keep partial ownership of the IP." That would mean you've analyzed a large number of games by all the publishers, at least enough to come to a conclusion. I'd like to see the side-by-side comparisons, if you don't mind.

Regardless, what I don't really understand is the idea that co-owning an IP means Nintendo "trusts" developers more.  That doesn't make any sense.  That still means Nintendo controls the fate of that IP.  Nothing can be done without their permission.  Why does that imply trust?  Wouldn't "trust" be funding a project while letting the developer retain full ownership of the IP?

For example, I believe Fuse is owned by Insomniac--wouldn't that make EA more "trusting" than Nintendo?  Sunset Overdrive is also owned by Insomniac--doesn't that make Microsoft more trusting?  Off the top of my head, I'm pretty sure Titanfall was owned by its developers before they sold out to EA.  Not that it really matters, as the contract is the important part.

Actually, if you want to talk about trusting, wouldn't Activision win?  Destiny is solely in the hands of Bungie now that their partnership is over.  

I've got to be honest, here.  Taking partial ownership of an IP seems less trusting to me than some of what we've seen elsewhere.  

It’s false to say that Nintendo is the only company that has cooperative ownership of games, this seems to be common practice.

It depends on the copyright laws. Keep in mind, trademarks and copyrights are different things.

For example, some company called “Natsume” owned the trademark for Harvest Moon, but the copyrights are owned by Marvelous, so Marvelous is able to release old Harvest Moon games under the name “Story of Seasons” through their own localization firm XSeed. But Natsume has no rights to the game, even though they own its name.

But copyrights for videogames are a little more complex since there are multiple elements with different rules, and they are not necessarily seen as one entity. There’s music, art, code, and written story.

Additionally, laws across international borders (especially those not in the TPP) have some major hurdles if they are developed between multiple countries. GE007 is basically impossible to port due to many companies holding a stake in the game and having differing agendas.

There’s also the matter of old laws applying to certain properties. So even if things are updated, that doesn’t retroactively apply. Additionally, contracts of ownership may apply. Perhaps companies (such as Nintendo) maintains an old custom due to tradition.

I am not sure all the rules for Japan (or any, really), but I’d say that’s probably the reason why Japanese companies co-own copyrights for videogames.

Actually, I'm pretty sure the OP is right when he says that Astral Chain is at least a partially owned Nintendo IP. Nintendo released a schedule of first party releases that included Astral Chain. And since first party titles are really decided by IP ownership and not the development studio (hence Yoshi's Crafted World, Mario Tennis Aces and the like being first party), it makes sense to believe Nintendo do at least own some of the Astral Chain IP. This is similar to The Wonderful 101 being Nintendo owned. 

Notice how Marvel Ultimate Alliance 3 isn't included, even though it is a published exclusive.

Astral Chain is in the same situation as The Wonderful 101. The IP is co-owned by Platinum and Nintendo. Platinum can't do anything with the IP if Nintendo doesn't want and viceversa.

Technically those would be second party games. Games developed by Nintendo owned studios are first party since the are directly from the platform seller. Second party are where Nintendo is the purchaser of the services of a third party in order to develop a game, and this applies to exclusive dev houses partially owned or contractually bound to Nintendo despite not being owned directly by Nintendo. While third party games are supplied by an independent studio without the first party purchaser/contracting relationship.

Pokémon and the DKC trilogy are perfect examples of second party games. Super Mario Galaxy or Breath of the Wild as first part games. Final Fantasy 7 Remaster as a third party game.

Actually I don't see how it is any different to any other publisher. If a game is developed by X, you have to credit X, even if it is published by Y and Y owns the IP.

So SEGA and Platinum for Bayonetta for instance. I actually think in this case Platinum even co-owns the IP.

I doubt Bandai Namco can release a Souls game without From Software. There seems to be a co-ownership in place too.

When Bungie split with MS they made a deal about Halo-ownership, which indicates beforehand Bungie had some rights on the IP. Later on they published Destiny through Activision, but had a time-limited deal with Activision after which they regained full control over the IP.

I actually cannot think of an example of an IP developed not in-house by a publisher and the publisher takes full control of said IP. It might happen, but it seems Nintendos stance on this isn't so extraordinary in the industry.

I am sure that is the case, still it is nothing related to Nintendo. Look, NamcoBandai publishes the Souls-series, but they don't have full control without From Software (and Sony in case of Demon's Soul).

I'll add that Activision just published about 15 pieces of content for IP they didn't own - Destiny.

Well, maybe, we usually don't know about the contracts and can only imply. But the indication of the OP was the credit given - and that is demanded by most copyright laws. Even if you own the rights to the IP all creators have to be properly credited. So for us is no visible difference between Fire Emblem and Kirby on one hand and Souls and Bayonetta on the other. Credit has to be given to the developer, so they are credited in each case.

---------------