AU Bio: 

An AU where the casts for Digimon Ghost Game and Youkai Watch Shadowside are switched. Their main partners remain the same, although they are adjusted to fit the storyline better, and some plot elements are brought from their original show.

Shippings: 

Nomura Koutarou x Amanokawa Hiro, Tsukiyono Ruri x Higashimitarai Kiyoshiro, Arihoshi Akinori x Tsukinami Touma x Amano Natsume x Himeno Ayame

Characters: 

Ghost Game: 

1. Amano Natsume (replaces Amanokawa Hokuto)

She disappeared when Keisuke got into elementary school, leaving a mystery behind for her friends and brother. No one knows where she went, but her brother grows bitter because of this. During an unknown time, she meets and takes in Banchoumon, who becomes Keisuke's partner. She also created a Digivice called the Elda Digivice, and left it in Keisuke's hands. 

2. Amano Keisuke (replaces Amanokawa Hiro)

After his sister's disappearance, Keisuke grows bitter and angry, choosing to stay away from anyone and everyone, especially since he had lost his only friend, Kenji, to an accident as well. However, after meeting Digimon and Banchoumon, he takes a liking to Banchoumon and becomes his partner. Keisuke may seem obnoxious and dumb at first glance, but he notices things others don't and uses it to his advantage, also having a soft side. He still snarks a lot to hide the pain in his heart, even if the others can see the true him behind the mask.

3. Arihoshi Akinori (replaces Higashimitarai Kiyoshiro)

Akinori was one of Natsume's closest friends with Touma, so her disappearance impacts him greatly, becoming secluded and a bit obsessed with finding her. This leads him to distance himself from Touma, focusing on studying so he can get a degree to know more and more. However, he eventually comes back to Japan, ready to find out what happened to Natsume. He cares a lot for his friends, and uses his vast knowledge of technology and urban legends, even founding a forum so they can investigate.

4. Tsukinami Touma (original role)

Touma was another of Natsume's closest friends, and he had a crush on her even after she vanished, so even if he was bullied for being friendless, he continues to believe Natsume will come back. He spends time with Akinori after the disappearance and helps Akinori in a lot of things. He trusts his friends and Ougumon in dangerous situations, even willing to sacrifice himself for them, but it's a recklessness no one likes. Despite this, his kindness and care are present in every interaction he makes. 

5. Himeno Ayame (replaces Tsukiyono Ruri)

She is naturally curious and a bit interested in Youkai mythology, so she begins investigating Hologram Ghosts. However, this attracts Devimon and she falls prey to his inspiriting until Keisuke, Akinori and Touma meet her and help her defeat the Digimon with the help of Jorogumon. She is optimistic and always curious, asking questions about Digimon and their world a lot, and is always with Keisuke to ask questions about them. Despite that, she begins developing a healthy fear for their abilities, and begins understanding them more, trying her best to be kind to everyone, which more or less makes her popular with others. 

6. Banchoumon (replaces Gammamon) -> BoureiBanchoumon, ManjiBanchoumon

Banchoumon is a rare type of Digimon whose soul was formed in the human world after his death; he was known as Kenji before his death, although only Natsume knows this fact. Because of this, he's very kind and caring even if he's frustrated he can't remember anything from his past. He doesn't push Keisuke out of his comfort zone, and instead provides a space for Keisuke to cry when he's overwhelmed. He is a proficient fighter, mainly with his fists, and he doesn't like seeing his friends hurt. He is the final one to achieve his evolution, although he also has a dark evolution named ManjiBanchoumon, triggered when he is forced to watch his partner suffer in silent agony.

7. Suzakumon (replaces Angoramon) -> GuiSuzakumon

The calm one with smarts and rationale, Suzakumon is the perfect foil to the reckless Akinori. However, he was interested in Akinori due to his quiet rationale when the situation calls for it and has been watching over him ever since. He is known to talk calmly in most conditions but can be harsh when stressed out thoroughly. Despite this, he fights to the best of his ability and will not give up until the battle's won. This is how he's managed to unlock evolution first. 

8. Jorogumon (replaces Jellymon) -> OtsuchiJorogumon

A mischievous and manipulative person who loves playing with others, Jorogumon meets the team shortly after Ayame is saved from Devimon. She causes trouble for the team, but only Ayame trusts her and believes in her, allowing her to attain evolution shortly afterward due to their trust in each other. She does eventually soften up and helps them through the fights, unable to watch them get hurt.

9. 3 Ougumon (replaces Black Tailmon Uver) -Fusion-> Rasenmon

They're Touma's partners and they fight in their own way. There are three of them; Ogu, Mogu and Togu, with their own distinct roles, and they were the ones who led Banchoumon to Keisuke in the first place. They're very synced despite all the chaos they can cause and do their best to help Touma fight. Their trust in each other and love for Touma triggers their evolution, making him the second last one to evolve his Digimon.

10. Shukamon (original role)

It is implied that this Digimon is one of the few who can travel between the worlds, possibly being the one who brought Natsume to the Digital World. Nothing much is known of this Mega Digimon, though more shall be revealed eventually. 

Shadowside: 

1. Amanokawa Hiro (replaces Amano Natsume)

He is the one who is chosen by the Youkai Watch Vital to wield it since his dad, Amanokawa Hokuto, was a Youkai Acknowledger. While a bit salty, Hiro knows his strength and doesn't fight worthless battles, doing his best to stop GammaGamma from heading into battles just because of a bad feeling. He's childhood friends with Koutarou, and is the one to bring him back from the pit of despair and guilt. With the help of Koutarou's Youkai Watch, Hiro can shift GammaGamma into 4 different Shadowside forms. He's also very much gay, and it shows in how he interacts with Koutarou. 

2. Tsukiyono Ruri (replaces Himeno Ayame)

Ruri is a curious child with bouts of energy. She has an interest in Youkai which makes her feasible as a host to Draculania. Thankfully Hiro, Koutarou, and Kiyoshiro stop Draculania and save her. As a result of this, she becomes a member of the group. Angoran becomes her partner afterwards, having been her guardian spirit, and the two get along well, although they have their disagreements at times. 

3. Higashimitarai Kiyoshiro (replaces Arihoshi Akinori and Amano Keisuke)

Kiyoshiro grew up in a shrine and knows his way around the Youkai world, although this instills a fear of the supernatural into him, and so when Hiro searches for him to help him defeat Koutarou, he tries to pretend he doesn't know anything, but his Youma Radar gives him away. After Hiro convinces him to help, they go to recruit Jelly-chan, and he recognises the other as his childhood friend who was teasing yet cared for him a lot. The two then become partners in fighting against the numerous threats that come their way. 

4. Nomura Koutarou (replaces Tsukinami Touma)

Hiro's childhood friend, Koutarou grew up lonely and without many friends until Hiro came along, but even then Koutarou assumed Hiro just stuck with him for convenience's sake. It's only after he's beaten by Hiro that he sees the truth, and fights against Clock Lord with them to save the world from having its time stolen by him. From there, he can use the 5 Youseiken with his Youkai Watch Ken, which is specified to Kenbumajins, while activating 4 different Shadowsides for GammaGamma. He's a bit rude and offputting but cares a lot for his friends, mainly Hiro, and may flirt with some boys due to being gay.

5. GammaGamma (replaces Jibanyan) | Betel/Kaus/Weles/Gulus 

He was Hokuto's partner, but still retains his innocence as he becomes Hiro's partner. While his father had only unlocked Gulus as a dark form during his time as an Acknowledger, Hiro manages to unlock the other 3 as his battle-ready forms for 3 different situations. He is a curious child who loves chocolate with all his might, and he is also very protective of anyone he loves, such as Hiro. 

6. Angoran (replaces Seiryuu) | Symbaran

He helped the team when they were up against Draculania and ended up partnering up with Ruri following this arc. He is very wise and knowledgeable of Youkai, which comes in handy in the later fights, and he is calm in every situation. However, he can get secretive or hot-blooded during certain situations, which Ruri doesn't like until they settle their differences. Other than that, he cares a lot for GammaGamma and it shows in his interactions with him. 

7. Jelly-chan (replaces Komasan and Bourei Banchou) | Tesla-chan

She is the soul of Kiyoshiro's only childhood friend and the one who convinced him to become involved with Youkai again. While she is childish, she cares a lot for Kiyoshiro, never giving up on him. She does take on work from other Youkai, helping them with their various issues. She also cares for GammaGamma.

8. Clock Lord (replaces Oniou Rasen)

A malicious Youkai who tricked Koutarou into working with him so he could rewind time and change his past, he is actually an evil Oni who plans to steal everyone's time, only stopped by Hiro, Kiyoshiro and Koutarou. He returns briefly as a part of him ended tormenting Hiro for a while, but is swiftly defeated. 

9. Aoi & Mika (replace Saki)

They are Ruri's friends, although not much is seen of them. They support Ruri a lot and try to help her when she's in trouble, however, there isn't much they can do because it's Youkai related, mainly Draculania and the others to come.