Not gonna lie, I've got too much spare time.
Fullbring Arc Revised Because I Don't See Why Not: Part 2 (or 1?)
Ginjo visits Ichigo at the shop to scope him out but instead of showing a photograph of Isshin, he shows him his Substitute Shinigami Badge. Removes the unresolved question of whether Isshin had anything to do with Ginjo in the past (i.e. the one who gave him his Shinigami powers and got depowered) and speeds things along between them.
When Ichigo’s accepts Xcution’s offer to help regain his power, Ginjo uses his Cross of Scaffold to pass on his reiatsu to Ichigo so that he can awaken a Fullbring. It was intended to restore Ichigo’s Shinigami powers by kick-starting his own reiatsu upon mastering his Fullbring. Instead of it being said that Ichigo has a bit of reiatsu left inside him that no-one except these guys noticed, that so happened to manifest as a Fullbringer’s powers and finally implying that Ginjo gave that power to him.
This time it’s clear that it’s an ‘artificial’ Fullbring. But you get some clear parallels in Ichigo using a borrowed power to start of his journey but with a darker undertone since, instead of doing it to protect his family from immediate danger, he’s just incredibly desperate to get his power back. So much so that he’s doing the chest stabbing with a shady guy who hasn’t actually given him much reason to trust him.
I’d make some changes to the Fullbrings themselves such as Ichigo’s which would skip that stage where he’s throwing cross-shaped projectiles and instead manifests itself as the reiatsu shroud from the get-go. His training from there is controlling, maintaining and solidifying it whilst he fights. Also, I’d remove the aspect of Fullbring which requires another person to be around when it reaches completion since that seems uncharacteristic for a Hollow-type power and is just quite random.
(And when the Shinigami arrive, it really should be made clear whether or not they’re wearing limiters.)
Now the biggest changes are based around Chad who was meant to be the focus of this arc.
First up, to settle the differences between how Chad’s power works and how a Fullbringer’s power works, it’s made clear that he is unique among their kind. The how and why aren’t important but you could probably tie it in to being exposed to someone like Ichigo and/or Chad’s innate qualities. This uniqueness is displayed by how it manifests in two distinct forms, the power came with a name instead of being something he choose, it more closely resembles a Hollow’s power and using his own body and soul as the ‘object’.
It seems that the fact that his Fullbring is based on himself means that it doesn’t suffer from the same evolutionary limits as other Fullbring which are static objects and can take on multiple forms (e.g. Chad’s two Right Arms of the Giant). You could throw in that his Chain of Fate doesn’t corrode if you go with NGD’s alterations to the Fullbringers. This and his connection to Ichigo is why Chad was approached by Xcution long before going after their true target, planning to use him to convince Ichigo and later to steal this power for themselves.
In the meantime, Chad started dating Jackie. Because, at the end of the day, he’s a teenage guy and there should be
someone with an interest in women. And I could totally imagine Chad doing that thing where Ichigo asks how they got together, Chad explains it all in his head before just saying “and that’s how it isâ€. I swear he’d do something like that back in the day. But mainly, it just makes the eventual betrayal more impactful. [
Edit: Though this does make the second-most sympathetic of the group very...well, unsympathetic.]
When Chad meets Ichigo with Xcution and they start discussing Fullbrings, he actually explains why his coin wasn’t his Fullbring. Partly because he subconsciously reject the idea of the coin being a tool or weapon and because he was more inclined to his more unique Fullbring.
Ichigo training seemed like an excuse to show off some of the Fullbringers’ powers but I’d probably jump straight to a Yukio-provided battlefield with Jackie as his opponent from the start. Giriko and Riruka can demonstrate their pre-betrayal powers when fighting Tsukishima/Ginjo or something. Once his Fullbring’s active, that’s when Chad jumps in for the main training and they fight in a digitally-enhanced environment (like where Chad training by himself), maybe even throw in some game monsters.
In this fight, Chad’s showing off his Fullbring-tech-that-isn’t-his-Fullbring more than his arm powers to avoid splattering Ichigo and demonstrating his broadened skill. It’s pretty much meant to be a friendly spar. Chad’s enjoying himself because Ichigo had been one of the only people he thought could stand against him but they couldn’t fight because of personal beliefs. He also wants to show Ichigo how much he’s progressed in the meantime, and this is the first time in a while that they’ve actually been able to hang out like friends. The bromance is strong.
Then Ichigo completes his training with Ginjo and blah blah blah. Some mention of Orihime training her powers with Hachigen would be nice around this point. Kekkaishi!Orihime would please me greatly.
Next, Chad and Inoue fight Ichigo after being mindraped by Tsukishima. Neither go all out but they are pretty serious. The main thing about this fight is that through Tsukishima’s meddling, he’s brought out the buried feelings of resentment that they both have. How Orihime always felt helpless whenever Ichigo (and others) protected her or kept her out of fights. How Chad felt abandoned by Ichigo when he charged off to fight without looking back instead of helping him grow stronger. Maybe even on the side-lines you have Ichigo’s friends and family bitching about how he left them all out of the loop.
Then Tsukishima puts the icing on the cake by letting those two doing all the fighting since he could
never hurt his own ‘family’. At some point, Ichigo realises he has to go through them instead of around, and puts them both down hard before confronting Tsukishima. So yeah, plenty of emotional trauma there.
Then onwards to
the next part.
Edit: One last one then I'm done. Probably...
Substitute Shinigami Arc Revised Just 'Cause
Ichigo receives a standard soul pill which is designed to mimic the personality of their owner to act in their place. Instead of that storyline, Ururu has a malfunction whilst making deliveries which causes her to run wild and forces Ichigo’s intervention. Jinta, who’s helping Ichigo because Ururu’s a total beast, is one who explains their origins as mod souls who escaped being decommissioned and ended up in Urahra’s stock. He built them a gigai that functions a lot like a human’s body and allowed them to work in his shop. When the incident’s done, Rukia promises not to reveal them to her superior when she returns.
So we learn about SS being bastards with an explanation for who the hell Ururu and Jinta are meant to be and some foreshadowing for Urahara’s gigai-related antics. No Kon because the only thing remotely interesting about him is his backstory, imo.
Originally, Kubo was intended to write some story arcs for Tatsuki, Keigo and Mizuiro but his editors hurried him into introducing Shinigami. Not entirely bad since the monster-of-the-week could have gotten old at the time but much wasted potential, definitely.
So instead of the Kanonji arc, Keigo and Mizuiro get confronted by Yokochin and his crew someday afterschool. Looking for revenge on Ichigo, they drag the two to a condemned hospital to play a ‘game’ with them which mainly involves scaring and beating them (or maybe the pair run away but end up in the hospital). The Demi-Hollow gets incredibly pissed at all these delinquents running around in his hospital. When Ichigo and Tatsuki, who had seen them outside and followed, charges in to be a hero, it’s the last straw which yanks out the Plus’ Chain of Fate and causes a transformation.
Whilst they stat fighting the gang, that new-born Hollow reveals its ability to possess people and sneaks into Yokochini who has some kind of freaky transformation. Suddenly, Tatsuki getting her ass kicked and Ichigo pops out of his body to save the day. The battle brings down the hospital and the next day the group is dragged into the principal’s office.
Someone other than me would try to make Kon and Kanonji relevant to the story but I just don’t consider them worth the effort.
Next, there is the Hollow challenge between Ichigo and Uryuu. This time Keigo and Mizuiro get into their own confrontation with a Hollow which drags out their powers. And at the same time, Orihime, Tatsuki and Chizuru are attacked by a pair of Hollows instead. Tatsuki drags out her power first and kills one Hollow before collapsing, then Orihime brings hers out and kills another. Or you could do it the other way but I wanted to avoid Orihime being the damsel as much as possible.
Finally, at the end of the Hollow challenge between Ichigo and Uryuu, what appears isn’t a Menos Grande. Instead it’s the Grand Fisher who we were shown being turned into an Arrancar after losing to Ichigo. Ichigo ‘opens the tap’ when they fight and blows the Arrancar’s face off. Whoop whoop.