Shikamaru is a likely candidate. Given his intelligence, he could be the one who figures out Naruto's pranks quickly and tries to either foil them or help Naruto make them even better. He might see Naruto's pranks as an interesting diversion from the normal routine.
Sasuke could be one of the main characters. He might be initially annoyed by Naruto's pranks but then end up getting involved in some way, either trying to stop Naruto or joining in on the fun.
Well, it could be that Naruto pranks the clans to test their reactions and sense of humor. Maybe he uses simple tricks like fake summons or changing the appearance of clan symbols to see how they respond.
One of the interesting pranks could be Naruto disguising as a clan elder and giving out really strange and comical orders. For example, he might tell the Uchiha clan to start wearing pink headbands for a week just to see their confused reactions.
Kakashi could also be a main character. He could be the one who has to deal with Naruto's failure in a different way than Iruka. Maybe he has to decide if Naruto is worth another chance. Also, Sakura could be involved. She might initially be disappointed in Naruto but then realizes that there is more to Naruto's failure than meets the eye and tries to support him in her own way.
Obviously Naruto would be the main character as it's about him being the 'god of pranks'. His friends like Sasuke, Sakura, and Kakashi are likely to be important characters too. Sasuke might be the target of many of Naruto's pranks, which could add some humorous tension between them. And Kakashi, as Naruto's teacher, might be constantly trying to stop Naruto's pranks or get caught up in them.
There could be a member from each of the four clans as main characters. For example, a strong - willed Uchiha, a wise Hyuga, a brave Aburame, and a resourceful Nara.
Well, the Celestialsapien could have a special connection with the Uchiha clan. Since the Uchiha have powerful Sharingan abilities, the Celestialsapien might be interested in studying it or even enhancing it for some of the clan members. This could lead to a new kind of power-up for the Uchiha in the fanfic.
Obviously Naruto is the main character as he is the one usually pulling the pranks. His friends like Shikamaru might also be involved, either as victims of the pranks or as accomplices. Sakura could be in there too, perhaps getting annoyed at Naruto's pranks or being part of a prank on someone else.
The main character is Naruto for sure. When it comes to the Anbu, there could be some new and original Anbu characters created just for this fanfiction. They could have unique abilities and personalities. Naruto's relationship with these made - up Anbu characters could be really interesting. He might prank them in ways that play off of their individual quirks. For example, if one Anbu is really proud of his speed, Naruto could set up a prank that makes it seem like he's much slower than he thinks.
From 'Baka and Test', Himeji could be popular in the fanfic. She's smart and cute, and her interactions with the 'Naruto' characters would be interesting. And then there's Sakura from 'Naruto'. Her growth as a character and her skills could make her a favorite in the 'naruto baka and test fanfic' as she tries to navigate the new situations.
Sakura could be a great main character. You could show her growth during the bell test, not just as a ninja in terms of skills, but also in her self - confidence. Maybe she has to take the lead when Naruto and Sasuke are incapacitated for some reason.