The creator is definitely a fanboy of many things. In the case of Legend of the Rising Star, this notes off pretty much everything that's either from franchises that can't be intergrated into the story or interesting little things on the side:
Peacock already fills half of the page for the Skullgirls shout out page, but in Legend of the Rising Star, she brings even more to the table—
Her second form (brought upon by her Tsuki item) is based off of Riku, including a blade called Thousand Eyes which it in of itself is shaped after the Keyblade of People's Hearts.
Costume-wise, she's made to look like an archetypical Dastardly Whiplash villain, long collar and all.
Oblivion Agony is a combination between Argus Agony and Dark Aura.
The form's name itself is called Demon Hunter— both a reference to vampire hunters and her current job in Legend of the Rising Star.
Bulleta's Shotgun Reaper form bears a striking resemblance with to an Unversed creature. Even more coincidental that the form is born from all of her negative feelings.
Her Shotgun Maiden form is based off of not only her Midnight Bliss form, but also Blair the Cat's humanoid form, complete with age up and fanservice.
The Black Sun Slayer twin handguns were based off of Alucard's Casull and Jackal guns.
In Ode to Tactics, Double turns into Phantom Ganon when she goes up to fight Link, appropriately.
Nero Potenza and Asmodeus share similarites to Crona Gorgon and Ragnarok, being that one is a helpless wimp to a bullying creature that is technically part of them, along with being incredibly skiled swordmasters.
Kurai Tochi, Tone Rion's living guitar, is designed after Soul Eater's scythe form and even shares some of his personality traits.
Augustus Octavia summoned a scythe during his possession in Lunacy Carnival— It was called Erebus and shared the same color scheme as Riku's Soul Eater, complete with a devilish blue eye.
Out of all the weapons Miku gets, there's one in particular— the leekbow Der Freischutz.
Kaito, due to being the frostguy, eventually gets a lance called the Tiefen Wessen Klaue, made by Karloff Benze himself. It stands for Deep Ones Claw in German.
His primary weapon is an ice lance called Levias, which is just short off of Leviathan.
Karloff Benze is based off a real-life German engineer, along with his name being taking inspiration from Boris Karloff, a famous horror movie actor from the 1930s.
Similarly, his best friend, Satoshi Miyamoto is named after a real-life Japanese engineer and Nintendo's very own Shigeru Miyamoto. He also resembles Colress from Pokemon Black 2 and White 2.
The Sacriloids are all based off of their counterparts from Alice Human Sacrifice, notwithstanding the new additions-
Silent Empress - The queen and the clover
Princess of Madness and Lightning Margrave - The two twins and the golden heart
Bonus - Since the spot is taken up by Len and Rin, they also share similarities to the Daughter of Evil series.
Count of Icy Death - The singing man and the diamond
Hellfire Chevaleresse - The red woman and the spade
Lunacy Witch - The dream, complete with the freaky scars across her face and body
Since it's taken up by Luka, it's also a reference between the Tailor Shop on Enbizaka.
The Violet Archduke - Duke Venomania
In fact, the entire ranking system for the Apocalytes was based off of the Chess Pieces, with Demedis slightly based off of Phantom.
The Nightmare Campaigns were also based off of the War Games.
Species-wise, the Apocalyeans take their inspiration from Bleach, with the Arrancar as the examples.
Miss Marshmallow gets a huge makeover, making her look a lot like the Privaron Espada Cirucci Sanderwicchi, complete with the Friend's Yo-Yo becoming the Freundes Guillotine, serving the same purpose as Cirucci's weapon.
Reversa is based off of Junko Enoshima in appearance along with a lot of previous character ideas that the creator had.
Monochroma is a combination expy of both Marie and Peacock, strangely enough— cartoony antics and goth-loli dress included. ( Which makes her eventual transformation into the Skullgirl all the more symbolic.)
She also has some Monokuma in there for her super form, fittingly enough, with said super form being named Monokuroma by the creator himself as a joke.
To add to the whole "cartoony" feel, she has a personality inspired by the Joker.