Capcom and Level 5. But I would rather they spend money to strengthen already existing relationships. For example, Dragon Quest VII and VIII are good. But a Dragon Quest VIII HD for Wii U would have been even better. Bravely has done well on 3DS, but a full, HD entry for Wii U would have been great. Handheld Monster Hunter is great for Japan, but a full HD version for Wii U would have been much better for the West. They've pretty much missed this this gen, would be great to take advantage of these possibilities next gen.

On the Rare Replay videos they still seem to have a lot of people working there who worked on Conkers Bad Fur Day my favorite game they ever made. So I would still like them back. Plus they still have the rights to that franchise that alone makes me want them back.

They really should buy Platinum Games, they fit with Nintendo's philosophies of development, also i would love for Sega/Atlus buyout too.

And maybe expand a little and fund/buy some western studios.

You might be confusing the fact that nintendos failing console is not a viable business proposition for many AAA game companies, with them being difficult to work with. 

I'd go with Capcom myself. They have a lot of great IPs to work with x )

Dat obscure title OP.

Anyways, I guess Platinum Games.

Capcom, Sega, Platinum and Level-5. Especially now seeing as the former two are falling down anyways. Level-5 is a great developer and Nintendo needs to keep them exclusive. Next Level, Playtonic and some Western studios would be a wise investment too. Nintendo still has some of that Wii/DS cash, they should be bloody well using it.

Yeah that is exactly what Nintendo needed to do 6 year's ago, but better late than never.

Nintendo should never rely on third party's to supply mature content on their consoles.

They should be making their own FPS to compete with COD and Battlefield and their own racing games to compete with Forza and GT.

Because that's how you build a fanbase and keep it.

aquisitions in Japan are definitely tough to pull off if I remember correctly

Nintendo's best candidates for aqcuisition are:
+Next Level Games - the only independent studio that Nintendo trusts with ip such as luigi's mansion, mario strikers, and punch out. It surprises me that they are not first party.
+Shin'en - Strong supporter of Nintendo through thick and thin. Their games also have high level of quality for an indie studio (not AAA, but excellent nonetheless)
+Koei Techmo - Definitely an interesting choice. Not a developer that has done anything ground breaking, but they definitely have potential to break out solid titles, and with a proper lead, they could truly grow to be a great asset
+Level 5 studios - Although I don't see this one happening, given level 5's great commitment and success on the 3ds, acquiring level 5 could lead to better and consistent support for handheld games

Unlikely to happen:
-Platinum - They seem glad to transition between consoles and probably won't be limiting themselves to an acquisition anytime soon.
-Capcom/sega - They are still to big to be acquired. Nintendo already tried to acquire more out of Namco Bandai, but all they could manage was the monolith soft team (great acquisition btw). Perhaps Nintendo could do something similar for Atlus with Sega, but I doubt this greatly

Acquisitions brought Nintendo two of their greatest studios in Retro and Monolith.

How long has been it been now since they splashed out and secured one? Have they even made an acquisition since Monolith in 2007? I'm not aware of any.