The biggest catch with studio acquisitions is that you might only buy the shell of a company, because it isn't uncommon for the talent to leave the studio after an acquisition. There's a reason why Sony set aside $1.2 billion in bonuses for Bungie employees that will be paid out over the course of the next few years, but the question remains what all these people will do once they've received their payout.

Nintendo's acquisitions have fallen in one of two categories:

1. Studios that have worked exclusively for Nintendo on multiple games in a row, such as ND Cube and Next Level games.
2. Studios that nobody else believes in and as a result are very cheap to obtain. Retro Studios is such an example.

The fundamental requirement is that the employees of a studio want to work exclusively with Nintendo, but typically even studios that Nintendo has worked with multiple times want to maintain their independence, so Nintendo does not go for an acquisition.

Platinum Games is a popular mention in this thread, but when you consider that they want to retain freedom even after an acquisition, they aren't a realistic option for Nintendo. That's why we see Nintendo engaging in a lot of collaborations where both parties benefit, but ultimately are free to go their own way after the project has been completed. There's basically one Warriors team of Koei-Tecmo who has been doing nothing but make Nintendo Warriors games for almost a decade now, but that doesn't mean that Nintendo needs to acquire it.

Do you think these studios would fit in? What are your options?

I' agree with those 2 points you mention, but axquire the Warrior team from Koei seems pretty un realistic i guess

Based in that 2 points I think the first reasonable move is to acquire Grezzo. They did the 3ds remakes for Zelda OoT and Zelda MM also a new IP like Ever Oasis exclusive on 3ds. And the loved remake of Links Awakening for the Switch

There's a thing nobody says and maybe is a good question to talk about... Nintendo has HAL Laboratory and Intelligent systems as internal developers but in the paper these 2 are second party. Should Nintendo make a move and make them 1st party??

Seeing your avatar:

They should have bought and saved CING.

Both are technically separate companies but are tied so closely to Nintendo that they might as well be first party, wouldn't make much of a difference.

Nintendo should buy Microsoft in the most highly leveraged deal in the history of mankind.

the difference is that technically someone can buy them and leave Nintendo side... maybe is hard to imagine that happening but not impossible