due to the mods removing each of the p4 symbolisms of the shadow selves, I have decided to put them here as a reference (however feel free to make your own interpretations)
will be splitting this into three parts
Shadow Yosuke appears as an animated frog with a whimsical body on top, an allusion of a proverb "frog in the well". Yosuke's Shadow represents his animosity toward living in a confined country town, as well as his wish for something of interest to happen. Shadow Yosuke, like the rest of the shadows to come, represents the reverse of his Arcana, the Magician. The reversed Magician represents one with power, but who is cruel and misuses that power. Shadow Yosuke has the power of insight into Yosuke's motives, but uses that power to mock and humiliate him. Upon transformation, it also tries to destroy the protagonist with its new strength, describing him as "(something) that bores me".
Shadow Chie represents the reversed Chariot Arcana. The reversed Chariot symbolizes envy, addiction, low self-confidence, and abusive control. These qualities come from her relationship with Yukiko: she is jealous of Yukiko's beauty and addicted to how Yukiko depends on her. While her bond with Yukiko may not be physically abusive, Chie emotionally controls the friendship; this is the reason the dominatrix theme brings physical form to emotional bondage felt by both Yukiko and Chie. It is symbolic of both a superiority and inferiority complex.
Shadow Yukiko takes the form of a "caged bird", with an emphasis on her large wings in a small cage. This symbolizes Yukiko's feelings of being trapped in her current situation in Inaba, since she is expected to eventually run the family business. Her life has been pre-determined for her, which limits any possibilities her future may hold.
Shadow Yukiko could represent the Vermilion bird (Suzaku in Japanese). The Suzaku symbolizes the fire-element, which explains her Arcana. She could also represent a phoenix, a fire-based bird which rises from its ashes.
While Yukiko represents the Priestess Arcana, Shadow Yukiko represents the reverse Priestess (known for poor decision making and intellectual conflict). Her Shadow self acts like a flamboyant "princess", expecting some magical "Prince" to come whisk her away from it all. She wishes to be saved from her life, yet runs from the Investigation Team, who are there to save her, upon their first and second encounters.
During battle she summons her Charming Prince, as if manifesting her wish for someone to come save her.
As the reverse of Kanji, Shadow Kanji represents the reverse of the Emperor Arcana. The reversed Emperor is one whose will is weak, misleading, and based on corrupted intentions. While Kanji may seem strong-willed, Shadow Kanji represents his fear of being shunned and desperation for acceptance; his social ineptitude. It is also misleading, as it seems to symbolize Kanji's repressed desires for other men, but is actually his repressed and confused sexual orientation.
During the boss fight, Shadow Kanji will cast Forbidden Murmur near the start of the battle. The attack will always miss Yukiko and Chie, while Yosuke and the protagonist will always be afflicted with poison (unless guarding). This is symbolic of how a lot of men view homosexuality as "poisonous" taboo.
Later in the battle, Shadow Kanji casts Roar of Wrath. The attack will always miss Yosuke and the protagonist, while Chie and Yukiko will always be afflicted with rage (unless guarding). This is referencing how Kanji views women as hateful and cruel.
The rose bouquet around the head of the Shadow are a reference to a genre of manga directed at men featuring masculine men (rather than the effeminate ones found in Yaoi manga) called Bara, the Japanese word for a rose. A rose can also be seen when Kanji appears in the arcade opening in Persona 4 Arena.