As far as I know, you can recruit all of them. The only limit is how many you can take into battle with you.

can you ever take more than four with you?

I don't think so. I think 4 is the maximum.

You can take 4 ninjas with you on one team, although, you can make use of clones to fill up all the slots, so you technically have 9 units then. Also in Ranked battle from lvl 55 (could be other, my memory is not perfect) you get 2 extra teams to use :)

Well he was asking if you could take more than 4 ninjas with you as in dragging your ninjas from their slots onto the formation board.

When it comes to ninjas recruitment, you can recruit all good ninja if you are lucky and patient.
However, for some high-bonding ninjas such as: Sage Naruto, Mei Terumi, Gaara,Raasa,Itachi (Susanoo), Sasuke (Susanoo) or any other with similar attacks takes time, so be patient.
You c*so recruit them using coupons on special events, as excange for earned points.
These are called collectible fragments.
You can recruit (Konohamaru Corps) in arena for example.
Kakashi (Beheading Sword), Itachi, Sasori, Deidara can be recruited as exchange for special coins you earn from events (Space Time Battle, Survival Trial,Group Contributions .. etc.)
Learn how to be patient for start of the campaign then you might get one of these.
So far I recruited 41 and my level is 74 with bonding level of 91.
Have fun and dont play for too long its not good for your eyes plus it heats your house or condo.
Depends where you live :)
This post was last edited by Tuxedo Mask at 2017-7-11 20:29 This post was last edited by Tuxedo Mask at 2017-7-11 20:30