What tutors would mostly affect up the metagame? I'm strictly talking about moves that were strictly TM's/Tutors in the past, not new moves altogether (i.e. an aura sphere tutor).
I'm praying gamefreak puts in a Sleep Talk tutor in. Two things off the top of my head that would occur would be a RestTalk+Guts set for Conkledurr and Confagrigos possibly rising up into OU. RestTalk+Guts Conkledurr would make for one of the builkiest and hardest hitting physical tank in the game. RestTalk means Cofagrigous can actually do something in the turns it is and stick around. 145 Defense and an ability as useful as Mummy isn't going to be wasted on a spinblocker. With Mummy, Cofagrigous makes an awesome Scizor counter and a counter to must physical threats in general that rely on their ability in some capacity.
Heatwave Tutor:
Zapdos and Honchkrow could now run it with LightningRod and Moxie
Superpower:
MoxieKrow
Outrage:
DD + MoxieMence
Headbutt:
The only hint of viability for Serene Grace Sawsuck: a 100% accurate STABed 60% Flinching move. Sawsbuck has Thunder Wave and Synthesis but not the bulk to be Jirachi or Togekiss.
FirePunch:
Haxoruss!! He'd happily drop Brick Break for this move. Skarmory is the main target. It still survives a Fire Punch at +1 (66.46 - 78.44%) but the unboosted attack has a chance to 2HKO. SD set would kill everything slower.
Ice Punch:
Gliscor will have a lot more to fear from Conkeldurr if he gets hold of this one.
Sucker Punch:
Every dark type would love this: Krookodile, Hydreigon, Scrafty
Heal Bell:
Dragonite coud run it with Multiscale.
Focus Punch:
Bisharp's sub set would love a better Fighting attack than BB. He could get Superpower too.
Those are a few that came to mind.