Hi Mangahelpers,
I am going to point out that Luffy is not using his rubber abilities as effectively as he could be.
Case #1: Luffy has never and probably will never change his shape in such a way that he is able to impersonate another person. Other people with rubber properties like Elongated Man can perform this feat. In other words, Luffy can perform feats like Bon Clay where he impersonates someone by changing his appearance-- Luffy can do this by changing the shape of his body, but he never has and probably never will.
Luffy can probably also turn into a shovel or almost any other type of tool, but he usually doesn't do it. This is a lack of creativity if you ask me or maybe the author deliberately avoids allowing Luffy to do it because it would cause problems in his story if he impersonates people.
Either way... Luffy is not being as creative as he could be. Other similar characters do many things he doesn't even try to do.
I'll point to a specific case in another series where someone who had these abilities was NOT using them to their full extent, and it was shown to him by someone very smart.
In the Flash, the Elongated Man was Ralph Dibny. Ralph used his abilities to stretch his arms, and turn himself into objects. But, one time, he he had his powers stolen by a villain named DeVoe. DeVoe explained that Ralph was never able to use the full extent of his abilities because he lacked imagination. He then demonstrated that Ralph was able to turn into other people by changing his shape, which is exactly what DeVoe did upon stealing his powers. After having learned of his lack of imagination, Ralph discovered that he had shapeshifter abilities.
Ralph Dibny Transforms into Some Other Dude
The same thing is true of Luffy. Luffy can change his shape into other people's shapes, he's a shapeshiter, but he has never tried to do it. Someone smarter would do it, though, if they had his abilities. Think about it! He can change his bone structure. That means he can create an entirely new face.
If Luffy can change his face to look like this just by being hit by Kaido... then he can for sure "will" his body to change shape on its own.
Case #2: If Luffy can shapeshift into a person, then he can also shapeshift into every normal Zoan except the myth ones because they have special properties.
Case #3: If Luffy can shapeshift into a person, or any animal, then he can shapeshift into almost any form of tool or object, too. He sometimes does... but, he mostly doesn't. Evidence includes: he transformed his hair into goggles. He turns his punch into a pistol. His entire body has emulated the weapon system of a tank "Rhinoceros Howitzer." He has been both big and small at times, too.
If you think about it... Luffy could be doing the same things that other people do with their fruits... but he's just not doing it. As mentioned earlier, he could be performing Bon Clay feats of impersonation or he could be pulling off inflation feats like San Juan Wolf. Actually he does! Luffy gets big all the time and all he does is blow air into his body-- that's inflating lol.
Speculation: Isn't it weird that Luffy doesn't create EXTRA appendages via his rubber abilities? He could make 1000 arms if he wanted to. What's stopping a guy who has control over his entire body and it has rubber properties? Nothing. He could very well make his own bone structures, musculature, and everything else. He could even make an extra heart. It's really just up to the imagination of the author. He could become an octopus with eight arms if he wanted to. His stretching is unlimited, too... there is no set limit on that. He could punch somebody on the other side of the planet. Hell, he could punch somebody on the other side of the universe if the author allowed for it.
Guys... if Luffy can turn into a "Giant" 100 times his size... what is stopping him from turning into a giant 1000 times his size... 10,000 times his size... 100,000 times his size... do you understand that the size he is at any point in time is not fixed? He can be any size. Any size, any shape. He can orient himself to anything. That's precisely why the Five Elders say it is the Most Ridiculous ability. His combat abilities are limited only by his imagination.
It's a good thing that Luffy isn't very imaginative... because if he was... they would be so so so so screwed. People sometimes wonder if Luffy will sometime use a bladed weapon like a sword.... well, he could... but it wouldn't make sense... because the fact is Luffy can create substances from his own body that are equally strong and sharp. His body, with Haki added to it, is as strong as any unknown material could ever be. It's like alien technology. There is nothing saying he can't turn his body into bladed weapons, either. All he has to do is will his arm into the shape of a sword and suddenly he's performing flying sword techniques that Zoro only wishes he could do. He can make his own body so strong that humankind would not understand how to recreate something as strong as it is. That's what his body is like. You KNOW this because most things would break if Kaido hit it, but Luffy's body doesn't.
