This Theory is based on Luffy and the potential he has shown and has yet to show. Every massive fight Luffy awakens some new power or form.
This isn’t power its just him possessing a very High level of Will being able to control himself even with 100 other people’s shadows being stuck in him.
First we have Luffy during his defeat at water 7 against Lucci he discovered his body had abilities.Then we have Second Gear which pumps his blood through his body faster then most people can handle. It not only pumps the blood faster but it makes Luffy in fact faster. It has the drawback of the more he uses it the more it wears out his body.
Then we have Third Gear, Luffy blew air into his bones making their density magnified but had drawbacks just like gear two. Once the technique is stopped Luffy turns into chibi Luffy for half the time he used Gear 3.
After a short time we see him awakening his haki during the time they faced off against Duval and the flying fish riders.
Then awakened more haki during Impel Down and even further at Marineford during the ‘War of the Best‘.
Also during the Marineford war Luffy was said to have the most terrifying power of anyone trying to conquer the seas.
The character I am talking about is the clearest thinking and observational characters in all the series “Hawk Eyes” Mihawk.
Upon returning to the ocean on their new adventures each strawhat came back a lot stronger with more potential then they had before the timeskip. While we were updated on most of the strawhats locations and the training they underwent.
With Luffy we did not see anything except small glimpses of the early days of Rayleighs training for Luffy.
Rayleigh left Ruskaina Island 6 months before the return to sabaody so Luffy continued his training upto the day the Kuja pirates and Hancock picked him up. So we have 6 months of training Luffy could have created new techniques we have yet to see. In 6 months he could have created a few forms since in less then 1 day he was able to create gear 2 and 3.
Last bit of Rayleighs training we saw was when Luffy created the King Kong Gun after that we know nothing.
We then advance to Fishman Island and we find out Luffy mastered Conquerors Haki and created a technique to set his arm on fire while it is armored in haki that resembles Ace’s Fire Fist. How this is possible I have no clue but it is a memento of Ace so we just let it go.
We also discover Luffy has the ability to understand sea kings when Shirahoshi wished to help Luffy.
After Fishman Island, Punk Hazard was seemingly uneventful when it came to advancement due to Caesar being a tool of Doflamingo and just like Jinbe said during Marineford and Fishman Island false power limits your own growth so Caesar was never meant to be a strong character.
We advance further to Dressrosa we see full extent of Luffy’s Conquerors Haki during his fight of Don Chinjao. After witnessing his friend being shot by Doflamingo Luffy snaps and goes on an all out assault upto the castle to face Doflamingo. It was then at this point that Luffy finds out about devil fruits can be awakened and we discover his Gear 4 for the first time.
Gear Four seems to be a combination of Gear 2 and 3, Luffy’s size, speed, and strength are quadrupled. Then after Dressrosa ended the crew went to Zou where they discovered a lot of things had happened.
After all the explanations Jack and his crew showed back up and started attacking the elephant that supports and carries the town and minks on its back. It was then at this time that we see both Luffy and Momo can both hear the elephant’s voice just like Roger and Oden could.
After Luffy and his alliance split up at the end of Zou arc Luffy and part of his crew heads to Whole Cake Island to rescue Sanji. Right off the bat Luffy finds and fights one of Big Mom’s Commanders after a 10 hour battle Luffy shows us Gear Four had another form: Tankman which is the same as Boundman except for the strength of tank man is dropped to increase defence.
This leads me to believe that Gear 4 has other forms but at the sametime I think Luffy is still holding back a lot.
So let’s count off the powers Luffy has then I will get more into the theory.
1: Strong will
2: Gear 2 speed increase the more he used it in the past the more it wore his body down. But later in the story he overcame that as seen in Fishman Island arc he used gear 2 many times and it never wore him down like in the past.
3: Gear 3 hardens bones and makes part of his body that of a giant. But when Gear 3 is used and it wears off he used to turn into chibi Luffy for half the time he was using Gear 3. Yet again in Fishman Island arc Luffy overcame the chibi part.
4: Power to attract people to his side without even thinking.
5: Conquerors Haki power to make weak willed people pass out
6: Armament Haki armors up the body to increase resistance and striking ability
7: Observational Haki many abilities rolled into one perceive whole battlefield and determine who is friend or foe. Perceive attacks speed and reaction time increased.
8: Red Hawk fire fist punch
9: Gear 4 Boundman overuses haki only can use this form for 5 minutes then has to recover for 10 minutes.
10: Gear 4 King Kong Gun while still in Gear 4 he uses Gear 3 ability and blows up a limb to giant level but still uses Gear 4’s armament/rubber quota while still having the massive boost of speed from elastiforce.
11: Gear 4 Tankman, this is the second full form of Gear 4 it is basically the same thing as Boundman but instead of focusing on strength like in boundman, tankman is a immovable object, this form is basically a defence but just like boundman it has a serious drawback. It uses too much of Luffy’s cholesterol he already overeats because its his bodies way of healing. But in Tankman he only has a short gap of time he can use tankman especially if he hasn’t eaten in awhile.
12: One other ability Luffy has every time he suffers a near or complete defeat he comes back stronger.
Now given all these powers and strengths he’s gained in such short periods and the leaps bounds Luffy has grown.
Luffy might still be hiding other stuff from us or he might even awaken new powers like his devil fruit.
We have seen twice in the series the mentioning of awakened devil fruits first was the demon guards of Impel Down and then Doflamingo.
Luffy’s awakening will probably take on the same form as Doflamingo being able to turn his surroundings to string but Luffy is not a thinker so using it the sameway is out of the question.
Luffy is the type of character that will go all out fist to fist so Luffy will end up using it someway that will benefit the fight. Use it on weapons or to slingshot himself back up towards an enemy.
Luffy has many more abilities and I would not be surprised another form or 2 ready just doesn’t think hes capable of using them in battle at his power level now.
Just like the first few times he used Gear 2 and 3 the drawbacks were terrible but just like them he will overcome the drawbacks from Gear 4 as well.
Luffy’s potential to get more powerful is endless his strong will pushes him forward against tougher and tougher opponents.
*Theory by Draven