Aura Sphere tutor would be cool, especially for pokemon like Cofargrigus, who has to rely on Hidden Power for coverage (since his offensive movepool is pretty much Ghost-type attack and Hidden Power) and Reuniclus, who would no longer has to rely on Focus Miss. There is also a couple of other new pokes that would be cool with Aura Sphere (Chandelure, Beheeyem, ect.)
Also, Recover/Wish/Other Recovery Move tutor. Seriously, there are SO many potential walls with the new gen pokemon (and even older gen pokeon too) that are lower tiered because they can't recover. My main example is Cofargrigus, with its only form of recovery being Rest (And it doesn't even get Sleep Talk!). Even Moonlight would be decent on it.
A hazards tutor would also be cool. Imagine something like Mandibuzz with Spikes (it could work, as it could potentially use broken bits of bones as hazards). Stealth Rock tutor that gives pretty much everything Stealth Rock (like the good old Gen 4 TM did) would be pretty cool as well.