The most notable example would be Rachel, whose overall appearance, outlook and attitude is perfectly similar to Shinku. Up to having the same English voice actor.
Ragna's also has heterochromia.
Jin shares his most notable traits with Suigintou. Including having an existing Rivalry with the main characters. As well as having a "Suigintou" color palette in Calamity Trigger.
Nu-13's overall appearance and emotionless attitude is a reference to Barasuishou. Both wears eyepatches (Albeit, Nu-13 can only be seen wearing an eyepatch in her "Younger Form"), both are clones of the originals, and both only show their emotions towards someone important to them.
There is a shout-out to Star Wars in Ragna's Continuum Shift Story Mode when Jubei tells Ragna of Kagutsuchi.
Jubei: The 13th Hierarchical City of Kagutsuchi. You will never find a more Wretched Hive of scum and villainy.
Another Star Wars shout-out occurs later in the game during Rachel's joke ending, when she equips Ragna with sunglasses that make every woman in Kagutsuchi (and for hilarity purposes, Jin) fall in love with him. Kokonoe's description of Bang's reaction to Litchi declaring her love for Ragna is "as if millions of voices cried out in anguish, and were suddenly silenced."
CS's "Help Me! Professor Kokonoe!" segments can be seen as shout outs to the Tiger Dojo Fate/stay night, as they're both only viewable upon attaining a bad ending, they're much more lighthearted and comedic in tone, and they both tell you how you screwed up and how you can get it right next time.
There's at least one shout out to Ken Akamatsu's Negima hidden in both games. Some fans speculate that Ishiwatari and Akamatsu know each other and are fans of each others' works.
A pretty large one is that Rachel Alucard to Evangeline, possible right down to the Expy level. However, her cross shaped attacks are more reminiscent of Remilia Scarlet. Considering though that Evangeline herself may be an Expy of Remilia Scarlet, this may just be a recursive sort of thing.
Arakune used to be a normal being, but he is now some sort of Eldritch Abomination. He is litterally consumed by madness, he isn't aware of what he is doing, and he repeats lines and lines with the same word over and over. In Story Mode, one of his losing scenes shows him as a creepy swirl repeating "Azure" ad nauseam. The resemblance with Giygas from Earthbound is striking.
Before you dismiss it too quickly, bear in mind that BlazBlue has a healthy sense of humor.
Fate route probably gets shouted out by... Bang, the overly idealistic 'Hero of Ikaruga', who is way too eager to follow his master's footsteps, and had a nearly impossible dream of winning Litchi's heart, same way like Shirou who is dead set to follow Kiritsugu's footsteps as a 'Hero of Justice', and never gave up loving Saber, even when she went back in time and die there. Most agree that even when Litchi joined NOL, Bang's love to her never dies out, and only time will tell if True End gets shouted out.
Unlimited Blade Works main shout out would come from Jin, after the discovery that he is the world's antibody and that Hakumen is his future self, resulting him losing his insanity (or traded it with a different one), similar on how Shirou starts seeing a harsher light of his ideals thanks to his future self Archer, who is the Counter Guardian of the world (similar to antibody). Hakumen himself became bound with the orders of Rachel, same way like Archer became the Servant of Rin... who has the same Japanese and English voice actresses like Rachel.
Heaven's Feel has elements of it running already. Tsubaki, being the lover of Jin who stays on the dark due to a jealousy with someone else (Noel) is similar to Sakura, the lover of Shirou on the route, becoming Dark Sakura as she is jealous with Rin. On the other hand, Litchi started to mirror Shirou in the case of her joining NOL to save Arakune even after knowing that they're run with bad people is the same like Shirou completely tossing his ideals aside to save Sakura; and in the same time, Litchi has become something like Rider during her tenure with Shinji, a fanservice-providing lady fighter who is deep down good, but is saddled with a cruel superior. Bang's involvement may also be seen as a reference whereas Bang is like Shirou while Litchi is like Sakura, as it is believed that Bang's Nox, Phoenix Rettenjou, is the key to save Litchi from corruption, same way as how Shirou used the Rule Breaker to separate Sakura from the Dark Grail.
The plot of Carl's joke ending resembles the "six mysteries" event in Kingdom Hearts II... with added hilarity. The sound of a crying girl in the restroom? That's the School Nurse Litchi trying to get into a miniskirt one size too small. It also references Detective Conan, for obvious reasons, and even Scooby Doo, since one of the group members calls them "Mystery Inc."
One of Ragna's costumes in Calamity Trigger bears semblance to The Joker.
Genesic Emerald Tager Buster references to Genesic GaoGaiGar. Tager even gets a GaoGaiGar palette as DLC.
Speaking of color palertes, Tager also has one referencing The Big O.
Makoto's full of Street Fighter references. While her fighting style is already similar to Dudley's, her Unlimited mode pretty much gives her his entire moveset (and taunt). In addition, her Astral Finish is an over-the-top version of the Seichusen Godanzuki, an attack used by hernamesakeMakoto. Unlimited Makoto can also perform the Abare Tosanami and the original Seichusen Godanzuki.
They're two Hospital Hotties with leerings to Hot Scientist (Litchi was before, Kyoko was after) with long black hair. They had an occasion wearing a lab coat too (Litchi on the back stories as her scientist days, Kyoko wears it all the time, even in combat), and both wear glasses all the time. They're also teachers (Litchi taught the Kaka clan, Kyoko is a Badass Teacher)
Both tangled/sided with the antagonist faction (NOL and Justice High), but their true personality seems to leer to actually good hearted people.
Though they seem professional/kind most of the time, when nobody's looking, they tend to be Lady Drunk (Litchi as seen in Noel's CT Joke End and Tsubaki's Gag Reel, Kyoko's All There in the Manual).
They're surrounded with two guys, one intellectual and so far is the one winning their affection (Arakune/Lotte Carmine and Hideo Shimazu), one Hot-Blooded guy who probably had one-sided crush on them (Bang Shishigami and Hayato Nekketsu, the latter of whom teamed up with Kyoko and Hideo in Project Justice)
For fun, during Carl's Gag Reel, what role does Litchi took? School Nurse, just like Kyoko.
Several characters also bear similarity to those from Mortal Kombat.
Ragna is Scorpion, right down to the powers and voice actor.
Jin is Sub-Zero.
Noel is a combination of Sonya and Stryker.
Rachel is essentially a female Raiden.
Litchi is Liu Kang but Jade playstyle-wise.
Tager is Jax.
Hakumen is a combination of Noob Saibot, Cyber Sub-Zero and Kenshi. Both Hakumen and Noob Saibot are the current versions of, respectively, the original Jin and Sub-Zero. Hakumen parallels Cyber Sub-Zero in that Hakumen is a cyborg version of Jin (who parallels Sub-Zero). Playstyle-wise, he is more identical to Kenshi.
Makoto is similar to Liu Kang in terms of playstyle.
Amane Nishiki is basically if Johnny Cage is gay and Japanese theater replaced Hollywood.
Tsubaki Yayoi/Izayoi is Sektor.
Yuuki Terumi/Hazama is a combination Quan Chi and Shao Kahn.
Arakune is a combination of Reptile and Noob Saibot.
Mu-12 is a combination of Cyrax, Sindel and Kitana.
Nu-13 is a combination of Sektor, Kano and Mileena.
Nine is a combination of Sindel and Quan Chi. Like Sindel, she is a mother of one of the protagonists and is brainwashed by the major antagonists, and like Quan Chi, she specializes in Black Magic.
Kokonoe is a combination of Kurtis Stryker and Kitana. Like Kurtis Stryker, both rely heavily on gadgets, and like Kitana, both are daughters of people who are brainwashed by the major antagonists.
Platinum the Trinity is Ermac. Both have multiple souls connected inside one body and their main soul is someone who has connections with the major characters (Platinum's Trinity Glassfield to the Six Heroes and Ermac's King Jerrod to Sindel and Kitana).
Valkenhayn is a combination of Nightwolf and Smoke.
Rachel is essentially a female Slayer. In a wink from the creators, Rachel and Slayer even share one of their KO poses.
Arakune is a combination of Zato-1/Eddie, Faust/Dr. Baldhead and Zappa, with a dash of No-Face. Like Zato-1/Eddie, both were formerly human and have similar origins (Arakune turns into an Eldritch Abomination as a result of Boundary Corruption; Zato-1 gets his powers from the Forbidden Beast Eddie and the latter takes over the former's body following his death), and like Faust/Dr. Baldhead and Zappa, both use a Confusion Fu playsyle.
Litchi is pretty much the combination of Millia Rage, Zappa, Venom, May and Anji Mito. She gets her powers in similar way as Millia (Boundary corruption and Forbidden Beast), one of her motivations is trying to find someone to cure him/her (Boundary corrution for Litchi and spiritual possession for Zappa), her weapon of choice is similar to Venom's (Litchi's weapon a staff and Venom's weapon a pool cue), and her relationship with Arakune mirrors Millia and Zato/Eddie, as well as them leaving their former posts (Sector Seven and Assassin's Guild). Like May, both are of Chinese descent. And just like Anji, Litchi is closely related to a pink-haired woman who is rather vengeful (Kokonoe as a stand-in for Anji's Baiken), wears glasses, and CS development had her join NOL, coming in conflict with Kokonoe who hated Hazama/Terumi... same way as Anji joined That Man, coming in conflict with Baiken, who hated That Man. Though consensus also say that despite being on the enemy side, they also have yet to turn into complete evil.
If Potemkin were a cyborg devil, Tager would most likely be the direct result.
Carl Clover is Bridget, and has recently spawned his Guilty Gear counterpart in the form of Bedman.
Hakumen is a combination of Justice, Ky Kiske, Faust, Axl Low, Johnny and Robo-Ky. Hakumen's appearance is identical to Justice's, his personality and motivations are similar to Ky's, parts of his appearance are identical to Faust's (both are ridiculously tall and their actual faces are never shown), both Hakumen and Axl Low are time travelers, parallel existences of characters in the timelines they're currently in and are British, both Hakumen and Johnny are McSamurai, and Hakumen being Animated Armor is similar to Robo-Ky.
Ragna, however does - in the fourth Teach Me, Ms. Litchi!!!, Ragna even complains about his low defense, and Litchi explicitly says it's "not as bad as Chipp Za-", while her thought bubble had a silhouette of Super-Deformed Chipp.
Considering their pink hair, grumpy personalities and revenge based motivations, Kokonoe is basically Baiken if she were a scientist and still had all her limbs.
Tsubaki's playstyle bears much similarity to Order-Sol. She even asks Kokonoe to refrain from comparing her to him in her Help Me Professor Kokonoe segment.
Hakumen's entire character fighting style is based off an older Daisuke Ishiwatari game, The Last Blade, back when he started at SNK. He plays much like a Power character from that series.
During one of CS's "Teach Me, Miss Litchi!" segments, Noel comments on how she had been trying to make herself smarter for her studies, and brings out the. "Ludovico Brain Flex-O-Matic model 1984." She said she saw an ad for one in a magazine and ordered it from the Orwellian Industries website.
For an old school Shout-Out, Hazama/Terumi has a lot in common with Richard Wong from Psychic Force. Both lived in a Crapsack World steered to satisfy their desires (Terumi feeds on hate, Wong always seems to get the happy ends for him). They can manipulate time and highly think of themselves as in the world's most awesome person. They manipulate a 'dark, antagonistic but may be well-intentioned' group (NOL and NOA) for their own purposes... with eyes closed. They also at one point turned a good Shrinking Violet member of the good guys into psychotic evil people (Noel and Emilio). And while Hazama is on his way to screw a hot female scientist (Litchi), Wong already screwed a hot female former scientist (Chris Ryan, turned into the combat cyborg Sonia, that he canonically got killed by the second game)
And coincidentally, Jin shares the same birthday (Valentine Day) with Keith Evans, who is the resident rival and ice user of Psychic Force.
Said in a very commanding and serious tone, Makoto's victory line at the end of a match parodies Fist of the North Star.
A possible reference in the English version when Hazama finishes of someone with his astral heat he will say "Please, just die for me".
One of Arakune's winquotes is translated in the dub as "What is a man?"
Tsubaki also seems to have similarities to LancerTrope CodifierKain. They're both the best friend of a more important character (story-wise), they are both more skilled fighters than said friend (Noel needs Bolverk to fight, whereas Kain deals more damage than Dark Knight!Cecil due to his Jump), and yet they are both ranked lower than their friend on account of favouritism (although, granted, Cecil was the king's adopted son while Noel is the victim of a Manipulative Bastard), and in both cases The Lancer is jealous of their friend's close proximity to their Love Interest. Also? Their respective Face Heel Turns are for the most part due to Envy.
Platinum's Astral Heat is almost identical to Marisa Kirisame's "Surefire Spark" spellcard from Touhou Hisoutensoku.
Litchi is called an "oppai obake" (lit. boob monster), the exact same nickname that Vita has for Signum
During Plantinum's encounter with Ragna, while insulting him Luna randomly calls him "Baldy." This is probably a shout out to Bleach's Hiyori, another bratty character who likes calling people "baldy" regardless of whether they actually are.
Another possible Bleach reference: one of Hazama's favorite insults is "trash." This is the signature insult of prominent villain Ulquiorra.
Unlimited Arakune's additional Distortion Drive from Extend is a direct lift of Zato-1's Dark Sentinel overdrive from the first Guilty Gear, though it functions more like the Dark Sentinel used by EX Eddie from XX onward.
Palette Swap References
In Continuum Shift, The first color in the first DLC pack is a reference to other characters, and is also from CT's DLC.
The #14 swap in Chronophantasma exchanges each character with another.
Ragna <-> Makoto
Jin <-> Izayoi
Hakumen <-> Tsubaki
Noel <-> Nu-13
Mu-12 >-> Lambda-11
Rachel <-> Valkenhayn
Taokaka <-> Arakune
Tager <-> Bang
Litchi <-> Amane
Carl <-> Relius
Hazama <-> Platinum
Bullet <-> Azrael
The #15 swap is a recall to Persona 4 Arena where Persona characters dress up as BlazBlue characters, but since not all BlazBlue characters were represented... italics refers to BB characters using the palette of those not playable in P4A.
His personality in joke endings is influenced by Gintoki, with whom he shares the same voice actor. Both Ragna and Gintoki are badass white haired swordsmen whose fear of ghosts makes them scream like girls. It is implied in the materials collection that Mori asked Tomokazu Sugita to be Ragna after he watched Gintama. This inspires various Blazblue x Gintama MAD videos.
Bloodedge, Ragna's time-displaced alternate self who fought the Black Beast, pays further homage to Gintoki by only wearing his jacket on the left side, much like how Gintoki wears his outfit.
Jin's brother may be the one who looks a bit like Archer, but in terms of what their job is...he pretty much fills in the role as a Counter-Guardian. Jin is described as the world's antibody after all. He's probably still in the Emiya Shirou phase, however.
Considering how the Nasuverse reference spree goes, Rachel filled in for Rin Tohsaka; not only she has the same English and Japanese voice actresses, she also summons and is essentially Archer/Hakumen's master. Then again, she looks more like Arcueid Brunestud...
On the other hand, her playstyle is identical to Order-Sol's.
Again with the Nasuverse references, she seems like the stand-in for Sakura Matou, being the most likely of Jin's love interests. She's also turned to the dark side (into a Green-Eyed Monster, precisely) due to frustration of someone (surprisingly, not the Rin counterpart Rachel) taking everything away from her.
Platinum has a male personality, a female personality, and a third personality which is ridiculously powerful. Hmm. What we're facing here is a loli Ryougi Shiki.
Her actual character design is an over-the-top parody of Sailor Moon.
Funny little note, if one notices, the third personality of Platinum is Ryougi... but in reverse. Where Ryougi can, more or less, destroy anything that she comes across being the personification of Akasha, Platinum's Trinity can create... anything. The odd thing is that Ryougi can recreate... anything... however this is a power of Akasha that she doesn't use all that much.
Makoto is an expy of Squirrel Girl, and her fighting style is very similar to Dudley's from Street Fighter. Her Unlimited mode takes this to its logical extreme as she gains several of Dudley's moves, and even a variant of his taunt where she throws an acorn at the opponent.
On the subject of Ace Attorney characters, Relius seems a bit reminiscent of Manfred Von Karma, as both are stoic and obsessed with achieving perfection, both are abusive towards their (adopted in Von Karma's case) sons, and even try to kill them when they get in the way. They are also very refined, and wear cravats. Not to mention their voices are both deep. All that's left now is for Relius to become a lawyer.
Saya appears to be the Aizen to Hazama's Gin at first.
In Jin's Arcade Mode in Continuum Shift. When he's resisting Yukianesa's influence on him, he says "Urusai!" three times in a row. Does this remind you of a certain Fiery RedheadedGirl who is also an aloof Tsundere and wields a Katana?
Mark Henry's use of a scarf as a whip and drill seem somewhat based on Rose or Iku Nagae.
Take Raoh and add in Kenpachi's code of honor, use of a Power Limiter, and an obsession with fighting the spiky hairedBFS wielding protagonist(Doubly so since Ragna has an Ichigo pallete now). That's Azrael in a nutshell.
In terms of Guilty Gear parallels, he's pretty similar to Slayer. They share several animations, the same style of teleport dash, a general playstyle, the unique distinction of their standing medium attacks (5B and Slash respectively) having a followup and a similar 6A shoulder charge. There are several story similarities as well.
Terumi's hoodie has already been the subject of Dr. Doom jokes.
Background-wise, Makoto resembles Nanael, being both fantastic beings with a cheerful personality, but with very screwed-up backstories, including being discriminated by their peers and both having human friends (Leina and Tomoe in Nanael's case and Noel and Tsubaki in Makoto's case).
Take a look at his Astral Finish, then notice the pose he takes afterward. He must've learned a thing or two from Akuma.
If you listen closely to his story mode dialogue in Japanese, you'll eventually realize that Kakihara is pretty much channeling Jun Fukuyama's "Zero voice." It makes even more sense considering his mask, which looks chillingly similar. He is even more reminiscent of Nightmare of NunnallyZero. This comes full circle when in CS he gains a Zero palette! All Hail Hakumen/Jin! and the realization that Hakumen's voice is based off of Lelouch's Zero Persona.
One of his palettes gives him red armour and blonde hair, which together with the green sword trails may remind some of another Zero.
One wonders if his name and Kitsune theme might make him a shout-out to the Big Bad of Ushio and Tora, the kitsune daiyoukai Hakumen no Mono.
According to Word of God, Ragna drew inspiration from another wanted man in red, Vash the Stampede. Also, there's stuff like the psycho-brother, dead female companion, (Rem may not have been Vash and Knives' sister, but damn close enough) the robot arm and the wing that comes out of his arm.
Noel is one to Guilty Gear. In one of her story mode paths she's forced to dress as both a Jellyfish Pirate and later Valentine's outfit.
Her entire fighting style is an homage to Equilibrium, from which many of her moves are explicitly taken.
This might be stretching a bit, but consider the fact Taokaka is a Genki Girl voiced by Chiwa Saito who doesn't wear pants... doesn't that also describe Francesca Lucchini? (Yes, the pantsless bit is important.)
A few references to Wolverine as portrayed in the Marvel vs. Capcom games, such as Hexa Edge resembling Berserker Barrage X or both having supers that create a double.
On the subject of Fullmetal Alchemist, Hakumen can be seen as a reference to Alphonse considering he's actually Jin who sealed his soul into an Animated Armor. Plus both mention their brothers quite often.
They might remind some of Tarvek and Anevka Sturmvoraus from Girl Genius. Mysterious father whose experiments have screwed up the family and who has provided a body for the Big Bad, sister transformed from human to something not...
He may also be a reference to JoJo's Bizarre Adventure, particularly Part 3 (on which the fighting game adaptation was based). As in the JoJo fighting game, the Carl player effectively controls two characters at once. Marionette Purple even sounds like the name of a stand.
Nu's armour design is reminiscent of Anubis. Specifically, the pointy ends of the legs combined with the wings. Now, if the armour had dog ears and a staff...
Hazama's Astral Heat has the same input as our dear Geese Howard'sRaging Storm. Geese's Raging Storm releases a series of shockwaves blasting above upon execution. Hazama's Astral Heat conjures a series of chains blasting above upon execution. Coincidence?
Tsubaki's Astral Heat is one big homage to Lenneth.
During Arakune's joke ending, Jin's shop has Sol's Fuuenken sitting on the table.
Relius Clover's Astral Finish is just one big shout out to hentai in general. The place looks like a crazy sex dungeon, the opponent is tied up (or in the case of Hazama/Tsubaki, totally willing/completely oblivious), and the doors close before anything can be seen or heard. While this may seem creepy the fandom has already started making fun of it, even going so far as to call it the greatest troll finishing move of all time.
In Bang's case, he has cinderblocks placed onto his knees in order to break his legs. This is a Shout-Out to an ancient Japanese method of torture as well as Darkstalkers, where this was the signature super of Bishamon.
Azrael's Astral is more or less a FalconPunch, with the addition of a scene afterward where he flashes his exposed back to the screen like Akuma.
Azrael also borrows a mechanic from a past Arc Systems Works game, as his Valiant Charger special incorporates Hokuto no Ken's Boost mechanic. Anyone who's familiar with the fighter probably shat bricks when they saw that, but fortunately, he can't lock you into an infinite loop with it. Well, he could originally, but they patched that out.
The Fist of the North Star references get kicked up a notch with his Unlimited Mode. Not only does he have a Rapid-Fire Fisticuffs move, he also has an Overdrive Distortion Drive where his Battle Aura flares up, and the number 7 appears above his super meter, which given the strong influence of Fist of the North Star in his design, it isn't much of a stretch to assume this move is a Musou Tensei homage.
Sector Seven seems fond of playing homage to SNK. Unlimited Tager in Chronophantasma gains Maxima's Bunker Buster, whereas Kokonoe does her own spin on Terry Bogard's Buster Wolf with her Assault: Broken Bunker Version 2.21 special move—complete with exploding mechanized gauntlets. Coincidentally, Unlimited Bullet receives Pressure Buster, a Distortion Drive that combines Rugal's Gigantic Pressure and Terry's Buster Wolf.