It's like BSD but if the goofy/serious ratio was set to 95/5 (rather than somewhere closer to 50/50), and there are aliens.
Has similar characters (same archetypes/roles) and setup (ie. gang v. gang v. gang/baddie).
The largest difference between the two is what the series focuses on. Main series BSD focuses more on story telling and character building while B3 focuses more on world building and the day-to-day shenanigans the protagonist team face.

-- Mini

-Both shows have a lot of female characters that seem similar to the 5 mew mews in comparison to “mmmt.”

Ichigo/Zoey = Taruto (they both protagonists who tend to have similarity personality: funny, silly, & nice, both have food names)

Minto/Corina = Charolette (both mean girls, friends with the main protagonists and tsunderes)

Lettuce/Bridget= Chitose (both are softe-spoken characters, both wear green, and both act polite)

Pudding/Kiki = Cookie (both are short characters, have short hair styles, and both of their names are foods)

Zakuro/Renee = Chips (both act mean characters, both females, and both are food names) -except Chips is the villain on the show not a protagonist.

Aoyama/Mark= Nachos (since they both wear blue, have long hair well only if Mark is in his Blue Knight form, similiar personalities, both are male characters, and help the main protagonists most of the time).

-both shows share the same “magical girl” trope, which is very common in anime.

-both protagonists are children (even though Zoey is a teen, that still counts as a child). Same with the 5-6 mew mews I’ve mentioned in their group, similar to how it is with the Taruto characters when most of the vat furries are children.

-Both shows have similar genres: comedy, action, slide of life, thrillers, supernatural, mystery, fantasy, etc.

-Both shows aim or most likely for pg 13 + audiences.

-Both main protagonists in 2 of the shows are half human girl/half cat hybrid.

-both shows has animal furries or animal character (kakipi in “mmmt” is the only different animal species I know of). Than in “Tmm” its a mix of animal furriers).

-Mmmt & tmn similarities have similar initials. Which are often mistaken for calling the anime “magical mew mew Taruto” instead of “magical meow meow taruto” which this is the correct title.

-both shows have a lot of characters in them.

-Both protagonists wear bells (tartuo has a bell on her bow tie, while zoey has a bow on her tail).

-most of the female furries in “mmmt” wear dresses, same goes for most of the females in “tmm.”

-both main protagonists yell out their spells/commands. When they cast their spells at their opponent(s), when they prepare to attack. Such as taruto’s is “Great tiger meow, meow!” And Zoey’s is “Strawberry bell full power!”

-both have similar plots. Magical cat girl must defend/save the world cliche. But hard to save the world when it comes to romance.

-both shows are underrated.

-both protagonists have same eye colors (well only if zoey is in her mew form she has pink eye color. Which matches the same color as Taruto’s).

-both main protagonists have side kicks.

-Both shows were released in the early 2000s.

-both main protagonists always say their catch phrases. Taruto says “meow” while Zoey says “Mew mew style, mew mew brace, mew mew power in your face.” Or says “Nyah!~” in the original Japanese version of “Tokyo Mew mew.”

-- RingsGo

-Both have female progtagonists who have magical powers.

-Both have cute girl characters.

-both protagonists are children.

-both shows have a flying animals in them.

-both shows are underrated

-similar genres: supernatural, fantasy, comedy, adventure, and slice of life

-both shows ran in the early 2000s.

-both shows have almost the same amount of eps. “Bottle fairy” has 13, while “Magical Meow Meow Taruto” has only 12.

-Both shows have only 2 songs in their franchises. The intros and outros.

-- RingsGo

The reason why this anime “Magical Meow meow Taruto” is very similar to this other old anime “Princess tutu.” Is because:

-Both main protagonists have the same aliases as “Princess.” When both of them aren’t actual princesses in a magical kingdom or castle. That they live in. They are not royalty. That’s just what they’re called/aslias or named most of the time.

-Both main protagonist characters are half animal/half human hybrid. When Taruto is a half human half cat, while Princess Tutu/Duck is half human half duck (with a secret identity).

-Both protagonist are female role/leads, who clearly look like children.

-Both main protagonists are heroines.

-There’s a male in “MMMT” named Nachos who’s tall and has a crush on the protagonist, it’s similar to how it was in “Princess Tutu” When Fakir developed a crush on Princess Tutu/Duck. Later in that series.

-Both main protagonists wear dresses.

-both animes have boring main characters (Iori & the other is Mytho).

-both characters often say their animal sounds frequently throughout the series. Such as Taruto says “meow” while Duck says “Quack.” As their habit of sounding like their animal species.

-Both shows had featured ghosts in them.

-Both of the female protagonists’ close friend groups are 2 female friends with them most of the time.

-both animes were released in the 2000s (this one 2001 while “Princess Tutu” is 2002).

-Both Duck/Princess Tutu and Taruto have a very similar personalities: they both Niave, both are a klutz, young, cute, heroic, (oh my goodness they both almost sound the same too).

-Both animes have similar genres: magical girl/supernatural, romance, fantasy, mystery, a little nit of horror, comedy.

-both animes are underrated, no longer ongoing & their mangas ended in the same years (2003).

-Both intro & outros are boring to listen to. To the point repetitive (which I’d often skipped).

-Both shows feature villians which some of them are elderly/seniors.

-both Taruto and Duck have the same hair styles (braids), both are small/short character in stature/height, both are heroines, as the main protagonists, & they both aren't so smart too.

I can see these 2 animes have tons of similarities.

-- RingsGo

Let's see...

- Parasitic aliens who forged a bond with humans (Parasites and Mecha-Ude)
- Our protagonist (Shinichi and Hikaru) gets fused with a unique kind of their species (Migi and Alma)
- They fight some baddies (enemy Parasites and the Kagami Group & some rouge Mecha-Ude hosts)

Contrast is that Parasites are organic while Mecha-Ude are mechanical creatures. Also, the female lead has no powers in Parasyte while she does in Mecha-Ude.

-- RamRol97

dark twist magical girl

-- Cherubiyo

To paraphrase a Phineas and Ferb meme: ＂If I had a nickel for every time a teenage female protagonist named Rin quit her ballerina career due to an injury, then decided to change her life after finding some hi-tech vehicle thingy, I'd have two nickels. Which isn't a lot, but it's weird that it happened twice.＂

Also, Highspeed's OP singer voiced Rideback's protagonist!

-- RamRol97

Let's see... person born in a specific period in time (Ancient Rome and Modern Japan) who have aspirations of great significance (being one of the greatest bath house architects in Rome and being a big-time game illustrator) who were displaced in Heisei-era Japan and are enthralled with the technological aspects of that period (public baths and bishojo game development) and decide to introduce what they've learned to that time period.

-- RamRol97

Guy in another world runs a pharmacy.

Contrast: Reiji Kirio was an ordinary salaryman at the time of his teleportation and when he was, he was endowed with pharmaceutical superpowers. Pharma de Médicis was once Kanji Yakutani who died of karoshi and got reincarnated in another world; he possesses chemistry-related powers.

-- RamRol97

Same comedy concept, different gender.

-- RamRol97

If you're into cute girls doing hi-tech sporty things, then you may want to watch these 2 series. The contrast though is that Battle Athletes Victory focuses more on individual sports while Extreme Hearts is more into team sports.
Also, ＂initially inexperienced lead crossing the road to glory＂ storyline.

-- RamRol97

Chainsaw Man and Jujutsu Kaisen both start with the main protagonist merging/combining with a demon or devil; CM's being Pochita and Denji, JJK's being Yuuji and Sukuna. Jujutsu Kaisen and Chainsaw Man see the protagonists as someone/thing that needs to be eliminated but will let them live on certain conditions, such as fighting against devils on a team or finishing what they started with the merge concerning a demon.

-- not_another_word

Gunslinging gynoids? Check.
Post-apocalyptic setting? Check.
Varied amounts of fanservice? Check.
Mobile gacha games? Checkaroo.

-- RamRol97

ZX is the direct sequel to the Zero series

-- RiskyZ

The protagonist is his parents' only son.

-- MUshiromiya1977

The same author wrote the source material for both OVA. Similar protagonists as both are overweight. The same studio animated each series. Hypnosis is a plot point in both.

-- Pluto34

Orange and AnoHana are both short drama series with 12 episodes and a movie. They also both have a supernatural twist.

-- hello_I_exist

Both are anime movies with romance and drama.

-- hello_I_exist

Horimiya and Toradora! are both short romances with elements of comedy and drama.

-- hello_I_exist

Ova of Jungle Emperor Leo

-- Ben6439

Ova of Jungle emperor Leo

-- Ben6439

Both games are produced by Yoshifumi Hashimoto and feature Kamil and Licorice

-- jakobhenerey21

First arc of Flame of Recca (tournament arc) copies extensively from Yu Yu Hakusho's Dark Tournament Saga. Also both series composed of a team of main characters (Flame of Recca used to have 4 mains just like Yu Yu Hakusho until a 5th member ed the party later on) and the main lead has a girlfriend who he must save from time to time.

-- DaiSenpaiSama

Domination

-- Kioute23654987

Both are an RNG-based military strategy game with same gameplay elements but a different setting:
KanColle - WW2 ships as girls fighting an abyssal organization bent on world domination
TouRabu - Feudal Japanese swords as boys fighting a retrograde force aimed on altering history, and sometimes a mysterious force that doesn't want any interference in the space-time continuum
Both are published by DMM.com, but have different developers - Kadokawa Games for KanColle, while Nitroplus for TouRabu.

-- RamRol97

A parallel story.
The same artist did the series and have the same orc antagonists.

-- lincasito

Both series have a similar feel, along with both focusing on romance, comedy and drama.

-- Karasu87

Both are isekais with horrible tsunderes abusing their love interest

-- maou

Ultimax is Arena's sequel,and takes place the day after Arena.

-- pyromania

Devil Summoner: Soul Hackers is an entry in the Shin Megami Tensei Series

-- pyromania

Persona 5 is an entree in the Shin Megami Tensei Series

-- pyromania

Persona 5 is a sequel to Persona 4, and is set about 5 years after Persona 4.

-- pyromania

Yu Yu Hakusho is Bleach, but shorter and with less filler. Both series feature a student, juvenile delinquent who meets a female shinigami and ends up working with that shinigami (who decides to also go to his school often) to help spirits travel to to afterlife. The series then changes to a battle shounen and the protagonist teams up with his friends to fight monsters.

Showing any more similarity crosses into spoiler territory, but the main difference between the series is that YYH focuses more on developing the characters.

-- AnneAuthor

The protagonist of this series also has a sister and a childhood friend, and that childhood friend has a mother who is a subject of infidelity.

-- SourNote2014

Cobre:The Animation is related to Space Adventure Cobra

-- king_Julius007

Both series deal with relations between human and non-human characters (vampires and ghouls) who live and work side-by-side. They both feature lots of violent, bloody battles with supernatural elements.

-- PunkHazard

Both series are psychological thrillers that weave together several stories and feature a mysterious assailant.

-- PunkHazard

Both movies are set in a futuristic metropolis and follow young boys/teenagers who are of street gangs. Both are fast-paced and violent with supernatural elements, but are essentially stories of friendship between two boys. They are both enhanced by rich, atmospheric music soundtracks.

-- PunkHazard

Both series star ruthless, white-haired child assassins who are emotionally detached due to their violent pasts, but who others feel drawn to and depend on.

-- PunkHazard

Both series take place in a distorted version of feudal Japan and feature two warriors/samurai and a young woman who are brought together by chance and embark on a journey together.

-- PunkHazard

Both are effectively Sci-fi Westerns. The main characters are both skilled fighters who have a complicated past and although they are really laid back, trouble seems to follow them around.

-- PunkHazard

Both are adventure/fantasy/comedies with supernatural elements and take place in a feudal setting.

-- PunkHazard

Both series follow the exploits of an oddball crew of space bounty-hunters.

-- PunkHazard

They are both surreal psychological thrillers from the director Satoshi Kon.

-- PunkHazard

Both series feature male characters with supernatural powers, who have a close relationship with a human-ghost girl.

-- PunkHazard

Both are slice of life comedies with touch of science-fiction. Both are centred around a schoolboy and his odd assortment of friends.

-- PunkHazard

Both series are comedies that involve organizations of heroes with unique, sometimes strange, abilities, costumes, and names. Both main characters are also outliers among the heroes - Saitama is extremely over-powered, while Izuku is the only hero at the academy without powers.

-- AmaterasuWings

Same animation studio. Same basic concept - after humanity has degraded, one species has pretty much overcome the human race - Titans in AoT, Vampires in OnS. A young guy (Eren, Yuuichirou) vows to kill all of the of the threatening species (Titans, Vampires) in a quest for revenge for dead loved ones.

-- AmaterasuWings

Both centre around a person u their lifeforce whenever they fight and people trying to save them from that fate.

-- LiCobra

Both series have Suzaku as the main God (school, for Yamada-kun to 7-nin no Majo) in which the protagonists siding with, and both animes has their protagonist gathering seven peoples in order to have their wishes granted. Both animes also deals with a book that has the informations about the warriors or witches. And they are also deals with time travel (Ancient China, for Miaka and Yui. And near past, for Ryu and Jin)

-- hikaruaizora

Similar purely by how crazy the plot is.

-- Rei

Pretty similar magic system, various adjustable magic devices.

-- Akikojam

Both take characters from our world and throw them into a fantasy world where their super OP powers save the universe by playing games.

-- Rei

Badass, seriously OP main character.

-- Rei

So many things are similar here: Character design; main theme(humans turning into monsters); smash cut zoom musical cues; and close ups on the eyes.
Given the fact that both series are the brainchild of Go Nagai, explains the similarities, as well as his expert way of telling so much with a mere close up of the eyes.
Spoiler: I found Devil Lady to be better with it's richer story line, but Dante has better plot twists.

-- Mitsugu

After viewing this again the music gave it away. There's a lot of similarity to the character design, and musical cues on top of the OST(excluding the main themes). The plot style isn't too dissimilar, though Angel Tales has no nudity or time travel. They're also both semi-quick series AT:13 eps + a bonus while Popotan: just 12.

-- Mitsugu

Same real world, just different years. Accel World is several years in the future from SAO.

-- Rei