As known by everyone, in each generation the Move Tutors return in the second installments of each generation and are increased in the third installment of the generation, which inherits most if not all of the tutors from the previous game. Similarly, the Move Tutor list rarely sees much difference, either due to Grandfather Clause or the lack of widely distributable high-tier moves. Each generation introduces about 10-20 additional new tutor spots for each game, with some others being replaced for other tutors. Other common occurrences are:
1)The counterpart move of an already existing TM or Tutor generally makes an appearance as a Tutor. For example, Pluck TM had Bug Bite Tutor, Quash TM had After You tutor, and so on and so forth.
2)At least one previously discarded TM move from the previous generation makes a return. In addition, another older generation move makes an appearance.
3)If there is a remake planned, some of the moves from that generation make an appearance, with them being most widely available in the said remake.
4)Each type has at least one Tutor.
5)Moves that can have a wide distribution are chosen for Tutors, much like TMs.
6)The additions to the Move Tutors are mostly biased towards new moves, much like other move distributions, in spite of the fact that they don't ignore previous generations as mentioned above.
With these in mind, we can start speculating for the next games' tutor list, starting with;
1)Terrain moves(Grassy Terrain, Misty Terrain, Electric Terrain): As rule 1 implies, previous area effect moves have been either TMs, such as the weather moves and Trick Room, or Move Tutors, such as Tailwind, Magic Room and Wonder Room. It is almost certain that the Terrain moves will follow this pattern, as they are representatives of three other archetypal elemental types that previous didn't have specific area effects for them(despite the fact that Sunny Day and Rain Dance granted some boosts to Grass-types, Solar Beam and Thunder respectively). Misty Terrain is especially likely, as it would provide a token Fairy-type Tutor move.
2)Ally boosting moves(Rototiller, Flower Shield, Magnetic Flux): As rule 1 implies, previous doubles/triples specific moves have been TMs, such as Ally Switch, or Move Tutors, such as Helping Hand. And similar to the area effects, these moves affect all allies that meet the specifications of their move. As such, it is likely that at least Rototiller will be made into a Tutor move. For Magnetic Flux and Flower Shield, as their distribution is lower, they don't have an equal chance of making in. Aromatic Mist is not mentioned, as it is currently Aromatisse's signature move.
3)Ion Deluge: Again, similar to the area effects and ally boosting moves, this move has a high chance of appearing as a Tutor because it is created mostly for doubles/triples. It's effect also provides a makeshift alternative for Volt Tackle for Physically offensive Pokémon that don't get it.
4)Guard moves(Wide Guard, Quick Guard): Though these were introduced in Gen V rather than Gen VI, they haven't been too valuable in that generation due to their less attractive mechanics, which have been buffed in this generation. In addition, before this generation they didn't have a large distribution. However, with the recent increase of priority and area moves, as well as with the fact that these guard moves gained a lot users from Fighting-type and Flying-type, it seems likely that they will be distributed more later in this generation. On the other hand, they already have a large distribution, as such they are not necessarily a top priority.
Aa-Other notable status moves:
1)Sticky Web: Though it is similar to String Shot and other entry hazards, Sticky Web seems similar to Quiver Dance, in that it largely exists to boost mediocre Bug-types and not much else. However, it has a potential of being a tutor for most larval Bug-types that are found early, much like Iron Defense is for cocoons.
2)Venom Drench: Venom Drench works the same as Venoshock, as such it doesn't have any balancing issues for its distribution. However, as its current distribution is mediocre it might not be considered important enough to be a Tutor.
1-Play Rough: Play Rough is a notable move for two reasons. First one is the fact that it is one of the most widely distributed new offensive move of Generation VI that is not a TM. The second reason is the fact that it is the only Physical Fairy-type move in the game as of now. Because of these reasons, I would believe that Play Rough has a high chance of appearing as a Tutor move.
2-Fell Stinger: Unlike Sticky Web, Fell Stinger actually enjoys a wide distribution outside of Bug typing. In addition, its nature doesn't differ much from Swords Dance, in fact most of the Pokémon that learn it can also learn Swords Dance(or the likes of Power-Up Punch). This combined with Game Freak's known preference for gimmick moves for their wide move distributions makes it likely that Fell Stinger will see a Tutor.
3-Petal Blizzard: As the rule 1 implies, Petal Blizzard is the physical Grass-type equivalent of Surf, and it is the only Grass-type move that hits more than one enemy besides Razor Leaf. As such, it is likely to appear as a Tutor. Another reason why it is likely to appear as a Tutor is its Base Power and its status as a Physical Grass-type move(as the only other widely available one is Seed Bomb).
4-Phantom Force: As rule 1 implies, Phantom Force is a Ghost-type two-turn move. It is also the strongest physical Ghost-type move in the game that is not a signature move. However, unlike the previous moves Phantom Force is currently only learned by Ghost-types and the legendary Yveltal. In addition, most of the physical Ghost-types have already access to it, or have access to Shadow Claw. Though Phantom Force can be distributed to Dark, Psychic and Poison-types in theory, its current distribution doesn't provide much optimism. However, its reasons for being a Tutor move are solid.
Ba-Other notable moves:
1-Horn Leech: Though Horn Leech is no longer a signature move and it is a physical variation of Giga Drain, most Pokémon that learn Horn Leech have either horns made out of wood, or are made out of wood and have horns. This is because its Japanese name is "Wood Horn." However, if Horn Leech is given to Pokémon that has horns, then it would be acceptable as a Tutor.
1-Belch: Belch is currently the strongest special Poison-type move, and it is one of the few widely distributed new Special moves of Generation VI that is not a TM. In addition, the move's mechanic gives Berry users a move that can't be used otherwise. Because of these, it has a good shot of becoming a Tutor move.
2-Moonblast: Moonblast is the other widely distributed move, as it is a Thunderbolt/Ice Beam/Flamethrower clone. It is also the currently the strongest special Fairy-type move in the game. However, the most important reason why it might be a Tutor is Arceus, as unlike its other types Arceus lacks a true offensive Fairy-type move, and it is not likely to learn other moves.
Ca-Other notable moves:
1-Draining Kiss: Though it is widely available and it is similar to other draining moves, Draining Kiss' Base Power is very low and the compensation for that, the amount of HP it restores, is not great. However, it is still not unlikely to become a tutor.
2-Boomburst: Strongest Special Normal-type move in the game and a move that hits all the Pokémon in the field, Boomburst has a deliberately low distribution, as it was meant for Normal Pokémon with low stats and non-Normal Pokémon with low offenses. Though most wish it to be Tutor to be used by Pixilate users, because its presence on the said Pokémon would make its' reason of existence moot and because most of its potential owners already have access to Hyper Voice, it is not likely to appear as a Tutor. If it does though, it would likely be given to Pokémon similar to its current roster, and hopefully Meloetta to so that it can have a better gimmick than its forme change.
1-On Rule 2, Discarded TMs of Gen V(Pluck, Work Up, Telekinesis, Ally Switch): Currently Ally Switch has a larger distribution than its previous distribution, and the only Pokémon that could previously learn it but can no longer learn it are genderless Pokémon such as Baltoy. As such, it likely won't return as a Tutor in this generation. Other extremely widely distributed TMs such as Captivate was ignored for Tutor role, as such Work Up might suffer the same fate, however unlike such moves it didn't gain much wider distribution. Pluck is a variation of an already existing move, Bug Bite, so it has a chance of return. Similarly, Telekinesis is largely created for doubles/triples and it had a wide distribution, so it might return as a Tutor as well.
2-On Rule 3, Gen III TMs and Move Tutors: Though it is hard to say what moves from this selection will be chosen, due to the recent 90's nostalgia boom, it is most likely that the moves will be chosen from the Gen III's previous Gen I/II moves. For reference either way, here's the remaining old move tutors and TMs:
1. Body Slam
4. Mega Kick
5. Mega Punch
8. Seismic Toss
10. Dynamic Punch
11. Fury Cutter
13. Defense Curl
3-Dive: Though it was previously a HM, Dive was granted as a Tutor in Gen IV, only to come back as a HM in Gen V. As it has been available for three straight generations and it is a two turn move, it will likely return this generation as well.
4-On Rule 2, The Token Old Moves: It's hard to say what will be the token old moves that will appear as Tutors, but it is reasonable to expect that they will be of the archetypes that don't exist in the Tutor list. Similarly, it is reasonable to expect that some of them will be selected from the moves that were modified in this generation. These can be;
Power Gem- Boosted to 80 BP in this generation from 70 BP, Strongest special Rock-type move, Strength's Special Rock-type counterpart.
Hex- Boosted to 65 initial BP in this generation from 50 initial BP, Potentially strongest special Ghost-type move, Venoshock's counterpart.
Future Sight-Boosted to 120 BP from 100 BP, One of the strongest Psychic-type attacks, Two turn move.
Hydro Pump- Nerfed to 110 BP from 120 BP, Strongest Water-type attack, Fire Blast's counterpart.
Aura Sphere- Nerfed to 80 BP from 90 BP, Second strongest Special Fighting-type move.
Hurricane- Nerfed to 110 BP from 120 BP, Strongest Special Flying-type move, Thunder's counterpart.
Synchronoise-Boosted to 120 BP from 70 BP, The other strongest Psychic-type attack, extremely gimmicky.
Regardless, the selection is much wider than these moves.
5-On Rule 1, Counterparts to new TM moves: Currently the new TM moves are Power-Up Punch, Confide, Infestation and Dazzling Gleam. Most counterparts of Dazzling Gleam and Power-Up Punch are already Tutor moves or TMs, whereas Confide has one counterpart, Play Nice. As Play Nice is mostly learned by early leveled Pokémon, it doesn't have much chance of getting in, especially since Confide is almost certainly going to be discarded next gen. As for Infestation, as partial trapping moves have gained a major boost in their turn based damage output, more of them might turn up as Move Tutors. However, Bind already exists as a Tutor move, as such it is not a high priority. If they appear, Whirlpool is obviously the likeliest to appear thanks to its wide distribution in Gen IV in its last appearance as a HM.
This doesn't mean that their counterparts(or other remaining counterparts of existing TMs and Tutors) will not appear, but much like Token Old Moves, one can only choose what is the likeliest to appear from a wide selection of possibilities.
Edit(21/05/2014): It should be noted that almost all of the Gen IV Move Tutors and TMs have been available from Dream World in some manner. The list as follows:
Gen IV moves that are not available as Egg Moves, Gen V Tutors, and Level-Up Moves:
-Ancient Power for Nosepass.
-Rock Climb for Tauros and Lickitung.
-Air Cutter for Beedrill, Butterfree, Mantine and Combee(note: Charmender now also gets it as an Egg Move.)
-Sucker Punch for Slakoth, Stunky and Nidoran Female(Note: Nidoran Female was incapable of learning it originally).
-Focus Punch for Teddiursa, Riolu and Delibird.
-Water Pulse for Snorunt, Castform, Lotad and Poliwhirl.
-Secret Power for a myriad of Pokémon.
-Brine for Psyduck, Slowpoke and Remoraid.
-Captivate for Clamperl.
-Endure for Growlithe, Seaking, Sentret, Taillow, and Meditite.
-Shock Wave for Pachirisu, Mareep and Wingull.
-Bullet Seed for Cherubi(Note: Roselia now gets Bullet Seed as an Egg Move).
-Fury Cutter for Beedrill.
-Natural Gift for Voltorb.
-Swift for Roselia.
Dream World Event-exclusive moves:
-Sludge Wave for Gastly and Koffing.
-Inferno for Misdreavus.
-Moonlight for Lunatone.
-Morning Sun for Solrock.
-Reflect Type for Kecleon.
-Superpower for Spinda.
Global Link Promotions:
-Double-Edge for Metagross
-Seismic Toss for Tyranitar
-Imprison for Gothorita
-False Swipe for Altaria and Jumpluff.
-Mirror Coat for Gothorita
-Cotton Guard for Banette
Overall unmentioned moves are:
Ominous Wind(Castform gets it both through Dream World and as an Egg Move)
Avalanche(Snorunt gets it both through Dream World and as an Egg Move)
Twister(Wingull gets it both through Dream World and as an Egg Move)
Other updated non-TM, non-early and non-Signature Moves:
Note: Flying Press doubles in damage against Minimized opponents and never misses against them.
Heal Block also now disables draining moves.