Spalk
Transformation jutsu is not just illusion. Naruto used transformation to make him and gamabunta kurama, they haved claws and fangs to catch shukaku. Naruto few times transformated into big suriken , his clones and saske throwed him like suriken and he was flying like suriken. Saske know it's Naruto because of weight.
I know that but if you think about it both transformation and body replacement are like plot holes in Naruto. They both are E Rank and in reality they are better than most jutsu. Imagine a character with scientific knowledge like Orochimaru abusing these jutsus. It would completely break the story. If I make transformation jutsu changing the properties of an object a character like Aizen by his nature must abuse it to its limit and this will immediately make him OP and destroy the story. The same with body replacement. A lot of fanfictions made this jutsu work like a small scale flying thundergod and It does not make sense.I will try to make the power system and the character a little more realistic. If Aizen comes into this world and immediately takes an E rank and makes it S rank it is like all the other characters are completely morons. I want to respect this world and it's characters and I want to make Aizen OP but through logic and serious scientific experiments.