It is required to read so the story doesn't have major loop holes, and for readers to understand Ben's power and his inability to control the transformation and use his powers accurately,
As Ben is just 4 years old so the diamond head transformation is a teen aged one unlike Ben's 10 year old when they look like adult full muscular and all, so the young age is a factor between the difference of usage of his to canon Ben.
Because of the interference of gods during his transformation, his full transformation uses environmental energy, but it also has a plus side that it provides more transformation,
Like when Ben will start using sage chakra he will have a new transformation for his aliens,
If Ben was in a normal universe like our earth Ben would not be able to transform into his aliens because it doesn't have any kind of usable energy that Omnitrix can use now , and also because only with his fusions Ben would be more than powerful to take over earth.
For transformation Omnitrix uses a large amount of chakra as large amount of energy is needed to change one's DNA structure, but the used energy for transformation is also released in environment when he reverts back to his original form,
This was the reason for the elder to detect some chakra fluctuations in Ben's household,
Even some people outside the clan area must have sensed it but they ignored it because it's the strongest clans compound,
After hiruzen became the third hokage he strategically and subtly used his influence to make his clan the most powerful clan, and also submerged the senju clan into other clans and slowly weakened the uchiha's, sarutobi goal is to make his clan the strongest as the patriarch of the sarutobi clan, and his friend danzo helped him in for mutual benefit of his shimura clan,
Truly the higer ups of konoha are a twisted group of old people.
Also Ben will secretly uses his fusion to get a grip on them but his most focus is on diamond head right now.
One of the reason is people feel threatened with someone else's power but they neglect someone's defence hence, he chose diamond head, and when he would able to control him to an adet level,
He will release other transformations gradually so, but not all will be revealed as as he will get the experience of using his alien transformation he will also develop a understanding for his other alien forms.
And also the academy arc will be soon after one or two chapters.
It will be small arc but expect a lot of comedy in it.
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Author out