In my first post, I gave Talents to the core 6 units, but I always had it in mind that some of the Talents that they started with weren't always the ones they finished with.
Kyoko is the Ult. Vocalist.
Esora is a Reserve Course. She was stripped of her Talent at the end of her first year due to a skirmish with the Togami Corporation to protect Rei and her family's honor, although the Togetsus never knew about it.
Ibuki started off as the Ult. Track and Field Runner, but during her time in Hope's Peak, she also became the Ult. Team Captain. Those parts of her memories were erased by the time she woke up in the D4 Killing Game.
And while Miiko is introduced as the Ult. Linguist, a later part of the story reveals that she is the Ult. Horror Enthusiast.
MORE SPOILERS
Another part of DR is Hope and Despair, so I wove that into D4 with the idea that during the Tragedy, Junko takes one member from every unit to be one of her Despairs.
Maho: Manipulated due to her insecurity of feeling useless compared to her unit mates, especially when looking at Talent. (Based off of plotlines in First Mix, and sort of All Mix).
Esora: Joined Junko to get revenge on Byakuya and reclaim her Talent. She worked with the Towa Conglomerate to build Monokumas and Monochios.
Saki: Traumatized after Junko separated her from her unit and made her think she witnessed Kaito's death. Junko's brain operation on Saki also messed with her Synesthesia and made her obsessed with finding new colors. Before Junko, she could use her Synesthesia to see the colors of people's emotions through their singing. After Junko, any form of vocal noise would trigger her Synesthesia.
Rika: Manipulated due to her savior complex. Because she was the one that inspired this crossover, I consider her Junko's favorite mastermind. They are both very impulsive after all.
Hiiro: Her Talent showed her that the only way to beat Junko was to join her first, so Hiiro put her love of mysteries to good use and did her best to be the perfect mastermind.
Haruna: Manipulated into thinking Kurumiiko killed Miyu, she went mad with grief and acquired an obsession for rule-following. She ordered the first execution and helped write the Killing Game rules.
Natually, Hope arises.
Rinku: (Does she need any explanation? LOL).
Yuka: Because of her connection to Mahiru, Sato, and Esora, she was also close to the Reserve Course and saw them as equal to Ultimate students.
Ibuki: She helped create the Future Foundation.
Rika: Even though she was a Despair, she acted as a Hope and was basically Rinku 2.0.
Aoi: Because everyone simps for her, in and out of universe.
Miiko: Because she wanted to be friends with everyone, and her true Talent of Horror Enthusiast gave her meta knowledge and made her genre-savvy, which was a huge threat to Junko.
After everyone is forced through the Killing Game, the Hopes change.
Rinku remains as her unit's honorary Hope.
Shinobu becomes Peaky's because she's always trying to move forward, no matter who the Killing Game takes from her.
Towa becomes Photon's because she remains supportive until the very end and is the only one able to talk Nozomi Kamukura into occasionally stepping down and allowing Noa Fukushima to take control of their shared body.
Saori, Marika, and Dalia are all deemed Ult. Hopes by Rika at the end of the game when she admits to them that she doesn't want to be a Despair anymore because they showed her how good Hope could be.
Tsubaki becomes RONDO's Hope as she, like Shinobu, vows to keep moving forward no matter who the Killing Game has already taken from her.
Miyu becomes Lyrilily's as the embodiment of forgiveness balanced with justice.
OTHER SPOILERS
Rika's REAL Talent is Arson (inspired by a running joke my friends and I have about Rika = fire) and she only hid behind the Volleyballer Talent to avoid suspicion.
She is also Masaru Damon's big sister. Their parents divorced when Masaru was a toddler, one parent taking each child. They never saw one another again, and when Junko found out, she implied that Masaru was dead, and that was one of the things that pushed Rika to Despair (although they reunite after Junko is defeated). The other was thinking she failed Tsubaki when they were kids (storyline taken from D4).
I also made a D4 version of Izuru, which is Noa's alter ego Nozomi/Kiko (which means Hope). Her backstory is that even though Izuru was conceptualized first, Nozomi/Kiko was created first, as it was easier to operate on a student WITH a Talent than one without.
While Izuru became an emotionless, indecisive Despair, Nozomi becomes a Hope obsessed with protecting the Cute and purging the Ugly. While Izuru's hair and eyes were black and red respectively, Nozomi's were white and cyan.
And the reason Haruna thought Kurumiiko killed Miyu was because Haruna was becoming increasingly isolated, trying to use her Chairman Talent to stop the Tragedy. Her unit members were trying to keep her from burnout and eventually went to Kurumi's big brother, Kokichi Oma (the white bird and the black horse). Miyu, Miiko, and Kurumi were the three female DICE members. Kokichi tricked Miiko into helping him hijack Kurumi's prank to make it more horrific and realistic, making them all believe that Miyu was dead. Kokichi did this both as a way to get Haruna to see where her actions were leading them, and because he perceived her as a rival for Kurumi's allegiance.