She-Hulk does have the capacity to control her transformation in the comics. This control often comes with practice and experience. However, there are instances where unexpected circumstances or powerful forces might disrupt her ability to do so.
Maybe it could be through some sort of magical jutsu. Naruto is known for his unique ninjutsu skills in his own universe. He might have developed a new jutsu that allows him to connect with and control the Hulk's mind. For example, it could be a jutsu that detects and manipulates gamma radiation, which is what created the Hulk. Or perhaps he found a way to use his chakra in a new way to interface with the Hulk's rage - powered form.
It could also have implications for the Hulk himself. Usually, the Hulk is a wild and uncontrollable force. But with Naruto in control, he might be able to be used in more positive ways. The Hulk could be directed to help rebuild instead of just destroy. And from a character development perspective, the Hulk might learn to control his rage better under Naruto's influence, and Naruto might learn new things about power and responsibility from having to control such a powerful being.
Sure, She-Hulk is related to Hulk. Jennifer Walters, aka She-Hulk, got her powers because of a blood transfusion from her cousin Bruce Banner, who is Hulk. This connection is a key part of their storylines in the comics.
Captain America would be a great addition. His leadership and moral compass could guide Hulk and She - Hulk when they face difficult decisions. And his combat skills could come in handy during battles.
In many comic versions, She-Hulk gets her powers after being exposed to gamma radiation, similar to the Hulk. But the details and circumstances can differ in different story arcs. Sometimes it's due to a scientific experiment gone wrong, or a deliberate attempt to gain powers.