I looked through the Analysis and Low Kick isn't mentioned anywhere on the Analysis. I was considering what moves to use on a Guts Machamp to absorb Statuses and hit hard with Rest/Sleep Talk. Close Combat really isn't desirable on a set that's designed to sponge hits, Cross Chop is only 80% accurate (when there's already only a 33.33% chance that you're going to pick it when using Sleep Talk), DynamicPunch is even Worse without No Guard, Brick Break is only 75 Base Power, and Revenge is set-up bait and doesn't hit Switches hard enough.
Then I considered Low Kick and the fact that Grass Knot is often used in OU because of its accuracy and how much most Pokemon weigh in OU. I then came up with this set:
Machamp@Leftovers/Flame Orb.
Adamant
Ability: Guts
EVs: 252 HP/252 Atk/4 Spd
Adamant nature (+Atk, -SAtk)
- Rest
- Sleep Talk
- Low Kick
- Payback/Stone Edge/Ice Punch
Leftovers if you want more survivability, Flame Orb if you don't want to rely on your opponent giving you a Status. Guts + Life Orb can also be rather fun, just make sure you're only getting Paralyzed or you'll be losing almost a quarter of your HP per turn, and that's BEFORE factoring other stuff like Sandstorm/Hail. Not to mention the actual attack Machamp will be getting hit by. So while it may be fun, Life Orb is generally not recommended.
This set really isn't that that innovative, just uses Low Kick for the Fighting STAB. Keep in mind, though, Guts makes it so that it Low Kick hits harder than No Guard DynamicPunch in all cases where Low Kick's Base Power is higher than 60, and regardless to say, its other attacks also hit harder than the No Guard variants after a Guts boost (Guts Payback and Stone Edge are essentially as strong as a No Guard DynamicPunch). I consider this set as sort of combining the Power of Guts sets with the versatility, survivability, and overall better reliability of the Rest/Sleep Talk set.
Sorry if I haven't tested it yet, but I just came up with it, so I'm going to try and do some damage calculations, please suggest some if you can think up of more, I'm just doing a couple right now as I'm going through the OU list.
So without further adieu:
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DAMAGE CALCULATIONS
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Vs. 252 HP/252 Def +Nature (Max Defense) Bronzong:
Guts Low Kick: 52.66% - 61.83%, 2HKO with Stealth Rock, likely even without.
Vs. 156 HP/100 Def Gyarados (Bulky Gyara) after Intimidate:
Guts Stone Edge: 70.81% - 83.24%, possible OHKO after Stealth Rock.
Vs. 4 HP Gyarados (LO Gyara) after Intimidate:
Guts Payback: 44.58% - 52.41%, 2HKO after Stealth Rock. Hell, LO Gyarados is left with less than 30% after switching into Stealth Rock and Payback anyway, so he can't really switch out and he can only attack 3 more times (except in the 7.7% chance that he survives with more than 30%).
Vs. 216 HP/252 Def Bold Salamence (The rarely-seen BulkyMence listed in the Analysis) after Intimidate:
No Guts Ice Punch: 53.25% - 62.60%
Guts Stone Edge: 52.73% - 62.08%
Guts Ice Punch: 79.74% - 94.03% OHKO after Stealth Rock.
Vs. 120 HP Adamant Salamence (DDMence) after Intimidate:
No Guts Ice Punch: 81.44% - 95.84%, OHKO after Stealth Rock.
Guts Stone Edge: 80.89% - 95.29%, OHKO after Stealth Rock.
Vs. 252 HP/152 Def Impish Hippowdon (Physical Wall Hippowdon listed on the Analysis):
Guts Low Kick: 54.05% - 63.57%, 2HKO after Stealth Rock, likely even without. For fun vs. 252 HP/252 Def Impish Hippowdon, it does 50.00% - 58.81%, so with Stealth Rock, even Max Defense Hippowdon is 2HKO'd by Guts Low Kick.
Vs. 252 HP/152 Def Impish Skarmory (Physical Skarmory listed on the Analysis)
Guts Low Kick: 40.12% - 47.31%. Still hits harder than No Guard DynanicPunch which does 33.23% - 39.22%, and Machamp needs to watch out for Brave Bird anyway, so Close Combat wouldn't really be desirable in this situation. Admittedly, though, the Confusion from DynamicPunch would probably more desirable in this situation.
Vs. 240 HP/76 Def Impish Jirachi (Wish/U-Turn variant in the Analysis):
Guts Payback: 38.15% - 44.89%. It actually does the same amount as No Guard DynamicPunch, though again, without the Confusion, so DynamicPunch would probably be better in this situation.
Vs. 252 HP/252 Def Bold Cresselia:
Guts Payback: 52.25% - 61.49%, 2HKO with Stealth Rock, likely even without.
Vs. 252 HP/136 Def Bold Rotom (Alternate forms, listed in the Platinum Updates section):
Guts Payback: 90.79% - 106.58%, OHKO with Stealth Rock, and most Rotom don't run this much Defense anyway.
Vs. 252 HP/96 Def Impish Forretress (Listed in the Analysis):
Guts Low Kick: 48.87% - 57.63%, 2HKO with Stealth Rock and Leftovers.
Vs. 252 HP/252 Def Impish Forretress (Max Defense):
Guts Low Kick: 44.07% - 51.98%, 64.3% chance of a 2HKO with Stealth Rock and Leftovers.
Vs. 252 HP/252 Def Impish Gliscor (Max Defense):
Guts Ice Punch: 96.33% - 113.28%, OHKO with Steatlh Rock, likely even without.
Vs. 252 HP/40 Def Metagross (Rest/Sleep Talk Gross listed in the Analysis, and the one with the highest defense):
Guts Low Kick: 57.97% - 68.13%. Since you're gonna be hitting him on the switch, though, DynamicPunch is admittedly better in this situation with its Confusion rate.
Vs. 4 HP Scizor:
Guts Low Kick: 96.45% - 113.48%, OHKO with Stealth Rock, very likely even without.
Vs. 252 HP Scizor:
Guts Low Kick: 79.07% - 93.02%, possible (though admittedly unlikely) OHKO with Stealth Rock. Still, Scizor can't do much to you back.
Vs. 252 HP/252 Bold Suicune (Max Defense):
Guts Low Kick: 44.31% - 52.23%, a good 68.2% chance of a 2HKO with Stealth Rock and Letovers being taken into account. Better than Close Combat in this situation, too, since Machamp would take less from Surf.
vs. 240 HP/216 Def Relaxed Swampert (Mixpert):
Guts Low Kick: 43.39% - 51.12%. Possible (but unlikely) 2HKO with Stealth Rock. This is probably a situation where Close Combat is better, since Relaxed Swampert is slower than Adamant Machamp. It's a definite 2HKO with Stealth Rock on the Adamant versions, though.
Vs. 188 HP/252 Def Bold Vaporeon (Wish Support Vaporeon listed on the Analysis):
Guts Payback or Stone Edge: 39.73% - 46.88%. Fucking annoying Vaporeon. As anyone who uses Grass Knot knows, Vaporeon weighs very little, taking 60 BP damage from Grass Knot and Low Kick. This is one of the situations where Cross Chop is probably the best move to use, doing 59.82% - 70.31%, a solid 2HKO, taking Stealth Rock, Leftovers, and 1 turn of Protect into account, though again it has accuracy issues, which becomes very apparent vs. Substitute versions. Hell, DynamicPunch would probably be better since Confusion h4x rocks. Vaporeon is the only reason you should consider Thunderpunch on Guts Machamp, as well as maybe a more reliable way of dealing with Gyarados. Though really, DynamicPunch does 71.43% - 84.15%, so DynamicPunch is a lot better in this case.
Vs. 252 HP/220 Def Bold Zapdos (Physical Defensive Zapdos listed on the Analysis):
Guts Ice Punch: 58.85% - 69.01%
Guts Stone Edge: 77.86% - 91.67%, OHKO after Stealth Rock.
Guts Low Kick (while Roosting): 46.61% - 54.95%
So sadly in this situation, you're going to have to rely one of your Super Effective moves since Guts Low Kick doesn't beat out Roost+Leftovers. Still, keep in mind, IMO, this set is a bit out of date. Adamant 252 Speed Lucario outspeeds this Zapdos and can guarantee a OHKO on this Zapdos with Ice Punch after Stealth Rock. So, let's see what happens against a typical Zapdos you'd see designed to take down Adamant Lucario:
Vs. 252 HP/180 Def Timid Zapdos (Zapdos designed to outspeed Adamant Lucario):
Guts Ice Punch: 66.93% - 78.91%, a possible OHKO with Stealth Rock, and easily done if it's taken more than 8% risidual damage.
Guts Low Kick (while it's Roosting): 53.13% - 62.50%. Sadly, still no guarantee of beating out Roost + Leftovers.
'course, Jolly Lucario can still outspeed that Zapdos and OHKO. So let's see what happens against a Zapdos designed to outspeed Jolly Lucario:
Vs. 252 HP/80 Def Timid Zapdos (Zapdos running enough Speed to outspeed Jolly Lucario, and putting the rest into Defense. Not very uncommon to see some Zapdos running this set these days, and actually it'd be very wise if they did if they aren't already);
Guts Ice Punch: 74.22% - 87.24%. Finally, a very good chance of a OHKO with Stealth Rock.
Guts Low Kick (while Roosting): 59.11% - 69.53%. Finally, it can reliably beat out Roost and Leftovers, so a Guaranteed 2HKO on any Zapdos running enough Speed to outspeed Jolly Lucario. If Machamp couldn't take out Zapdos, now you know that your Jolly Ice Punch Lucario can! And if Lucario was outsped, now you know Machamp can take it down easily!
Vs. 252 HP/252 Def Bold Weezing:
Guts Payback: 34.73% - 40.72%. Huh, guess Weezing has its uses after all. Not to mention Weezing is faster than this Machamp, so it can easily Pain Split to stall him out.
Vs. 252 HP/208 Def Impish Shuckle:
Guts Stone Edge: 59.43% - 70.08%, 2HKO. Shuckle fails at life.
vs. 252 HP Neutral Regirock after 1 Curse:
Guts Low Kick: 65.93% - 77.47%, easy 2HKO, but remember to watch out for Counter.
Vs. 252 HP/96 Def Neutral Spiritomb (Rest/Sleep Talk set in the Analysis):
Guts Stone Edge: 50.99% - 60.20%, 2HKO after Stealth Rock, likely even without.
Vs. 252 HP/252 Def Impish Dusknoir (Max Defense):
Guts Payback: 72.45% - 85.37% on the switch, 37.07% - 43.88% on the following turn (since Machamp is faster). 2HKO with or without Stealth Rock, though it does require prediction.
Vs. 212 HP/252 Def Bold Slowbro (Physical Wall set in the Analysis):
Guts Payback: 64.06% - 75.52% on the switch, 32.81% - 38.54% on the following turn. 2HKO after Stealth Rock, 45.46% chance of a 2HKO without Stealth Rock, again, requires prediction.
Vs. 132 HP Adamant Rhyperior (Subperior set in the Analysis):
No Guts Low Kick: 64.85% - 76.24%.
Guts Low Kick: 97.28% - 114.36%
Vs. 252 HP/252 Def Impish Donphan (Max Defense):
Guts Low Kick: 45.31% - 53.39%, possible 2HKO with rocks. Close Combat is probably better in this situation since it's a sure 2HKO with rocks and Machamp is faster, though Ice Shard might hurt a bit more with lowered defenses.
Vs. 0/0 Kingdra (DD Kingdra)
Guts Low Kick: 72.59% - 85.36%. Close Combat is probably better in this situation since it has a good chance to OHKO with Rocks.
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Comments, thoughts, suggestions? Am I onto something, or am I just grasping at straws?
Then I considered Low Kick and the fact that Grass Knot is often used in OU because of its accuracy and how much most Pokemon weigh in OU. I then came up with this set:

Machamp@Leftovers/Flame Orb.
Adamant
Ability: Guts
EVs: 252 HP/252 Atk/4 Spd
Adamant nature (+Atk, -SAtk)
- Rest
- Sleep Talk
- Low Kick
- Payback/Stone Edge/Ice Punch
Leftovers if you want more survivability, Flame Orb if you don't want to rely on your opponent giving you a Status. Guts + Life Orb can also be rather fun, just make sure you're only getting Paralyzed or you'll be losing almost a quarter of your HP per turn, and that's BEFORE factoring other stuff like Sandstorm/Hail. Not to mention the actual attack Machamp will be getting hit by. So while it may be fun, Life Orb is generally not recommended.
This set really isn't that that innovative, just uses Low Kick for the Fighting STAB. Keep in mind, though, Guts makes it so that it Low Kick hits harder than No Guard DynamicPunch in all cases where Low Kick's Base Power is higher than 60, and regardless to say, its other attacks also hit harder than the No Guard variants after a Guts boost (Guts Payback and Stone Edge are essentially as strong as a No Guard DynamicPunch). I consider this set as sort of combining the Power of Guts sets with the versatility, survivability, and overall better reliability of the Rest/Sleep Talk set.
Sorry if I haven't tested it yet, but I just came up with it, so I'm going to try and do some damage calculations, please suggest some if you can think up of more, I'm just doing a couple right now as I'm going through the OU list.
So without further adieu:
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DAMAGE CALCULATIONS
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Guts Low Kick: 52.66% - 61.83%, 2HKO with Stealth Rock, likely even without.

Guts Stone Edge: 70.81% - 83.24%, possible OHKO after Stealth Rock.

Guts Payback: 44.58% - 52.41%, 2HKO after Stealth Rock. Hell, LO Gyarados is left with less than 30% after switching into Stealth Rock and Payback anyway, so he can't really switch out and he can only attack 3 more times (except in the 7.7% chance that he survives with more than 30%).

No Guts Ice Punch: 53.25% - 62.60%
Guts Stone Edge: 52.73% - 62.08%
Guts Ice Punch: 79.74% - 94.03% OHKO after Stealth Rock.

No Guts Ice Punch: 81.44% - 95.84%, OHKO after Stealth Rock.
Guts Stone Edge: 80.89% - 95.29%, OHKO after Stealth Rock.

Guts Low Kick: 54.05% - 63.57%, 2HKO after Stealth Rock, likely even without. For fun vs. 252 HP/252 Def Impish Hippowdon, it does 50.00% - 58.81%, so with Stealth Rock, even Max Defense Hippowdon is 2HKO'd by Guts Low Kick.

Guts Low Kick: 40.12% - 47.31%. Still hits harder than No Guard DynanicPunch which does 33.23% - 39.22%, and Machamp needs to watch out for Brave Bird anyway, so Close Combat wouldn't really be desirable in this situation. Admittedly, though, the Confusion from DynamicPunch would probably more desirable in this situation.

Guts Payback: 38.15% - 44.89%. It actually does the same amount as No Guard DynamicPunch, though again, without the Confusion, so DynamicPunch would probably be better in this situation.

Guts Payback: 52.25% - 61.49%, 2HKO with Stealth Rock, likely even without.

Guts Payback: 90.79% - 106.58%, OHKO with Stealth Rock, and most Rotom don't run this much Defense anyway.

Guts Low Kick: 48.87% - 57.63%, 2HKO with Stealth Rock and Leftovers.

Guts Low Kick: 44.07% - 51.98%, 64.3% chance of a 2HKO with Stealth Rock and Leftovers.

Guts Ice Punch: 96.33% - 113.28%, OHKO with Steatlh Rock, likely even without.

Guts Low Kick: 57.97% - 68.13%. Since you're gonna be hitting him on the switch, though, DynamicPunch is admittedly better in this situation with its Confusion rate.

Guts Low Kick: 96.45% - 113.48%, OHKO with Stealth Rock, very likely even without.

Guts Low Kick: 79.07% - 93.02%, possible (though admittedly unlikely) OHKO with Stealth Rock. Still, Scizor can't do much to you back.

Guts Low Kick: 44.31% - 52.23%, a good 68.2% chance of a 2HKO with Stealth Rock and Letovers being taken into account. Better than Close Combat in this situation, too, since Machamp would take less from Surf.

Guts Low Kick: 43.39% - 51.12%. Possible (but unlikely) 2HKO with Stealth Rock. This is probably a situation where Close Combat is better, since Relaxed Swampert is slower than Adamant Machamp. It's a definite 2HKO with Stealth Rock on the Adamant versions, though.

Guts Payback or Stone Edge: 39.73% - 46.88%. Fucking annoying Vaporeon. As anyone who uses Grass Knot knows, Vaporeon weighs very little, taking 60 BP damage from Grass Knot and Low Kick. This is one of the situations where Cross Chop is probably the best move to use, doing 59.82% - 70.31%, a solid 2HKO, taking Stealth Rock, Leftovers, and 1 turn of Protect into account, though again it has accuracy issues, which becomes very apparent vs. Substitute versions. Hell, DynamicPunch would probably be better since Confusion h4x rocks. Vaporeon is the only reason you should consider Thunderpunch on Guts Machamp, as well as maybe a more reliable way of dealing with Gyarados. Though really, DynamicPunch does 71.43% - 84.15%, so DynamicPunch is a lot better in this case.

Guts Ice Punch: 58.85% - 69.01%
Guts Stone Edge: 77.86% - 91.67%, OHKO after Stealth Rock.
Guts Low Kick (while Roosting): 46.61% - 54.95%
So sadly in this situation, you're going to have to rely one of your Super Effective moves since Guts Low Kick doesn't beat out Roost+Leftovers. Still, keep in mind, IMO, this set is a bit out of date. Adamant 252 Speed Lucario outspeeds this Zapdos and can guarantee a OHKO on this Zapdos with Ice Punch after Stealth Rock. So, let's see what happens against a typical Zapdos you'd see designed to take down Adamant Lucario:

Guts Ice Punch: 66.93% - 78.91%, a possible OHKO with Stealth Rock, and easily done if it's taken more than 8% risidual damage.
Guts Low Kick (while it's Roosting): 53.13% - 62.50%. Sadly, still no guarantee of beating out Roost + Leftovers.
'course, Jolly Lucario can still outspeed that Zapdos and OHKO. So let's see what happens against a Zapdos designed to outspeed Jolly Lucario:

Guts Ice Punch: 74.22% - 87.24%. Finally, a very good chance of a OHKO with Stealth Rock.
Guts Low Kick (while Roosting): 59.11% - 69.53%. Finally, it can reliably beat out Roost and Leftovers, so a Guaranteed 2HKO on any Zapdos running enough Speed to outspeed Jolly Lucario. If Machamp couldn't take out Zapdos, now you know that your Jolly Ice Punch Lucario can! And if Lucario was outsped, now you know Machamp can take it down easily!

Guts Payback: 34.73% - 40.72%. Huh, guess Weezing has its uses after all. Not to mention Weezing is faster than this Machamp, so it can easily Pain Split to stall him out.

Guts Stone Edge: 59.43% - 70.08%, 2HKO. Shuckle fails at life.

Guts Low Kick: 65.93% - 77.47%, easy 2HKO, but remember to watch out for Counter.

Guts Stone Edge: 50.99% - 60.20%, 2HKO after Stealth Rock, likely even without.

Guts Payback: 72.45% - 85.37% on the switch, 37.07% - 43.88% on the following turn (since Machamp is faster). 2HKO with or without Stealth Rock, though it does require prediction.

Guts Payback: 64.06% - 75.52% on the switch, 32.81% - 38.54% on the following turn. 2HKO after Stealth Rock, 45.46% chance of a 2HKO without Stealth Rock, again, requires prediction.

No Guts Low Kick: 64.85% - 76.24%.
Guts Low Kick: 97.28% - 114.36%

Guts Low Kick: 45.31% - 53.39%, possible 2HKO with rocks. Close Combat is probably better in this situation since it's a sure 2HKO with rocks and Machamp is faster, though Ice Shard might hurt a bit more with lowered defenses.

Guts Low Kick: 72.59% - 85.36%. Close Combat is probably better in this situation since it has a good chance to OHKO with Rocks.
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Comments, thoughts, suggestions? Am I onto something, or am I just grasping at straws?