Kakugo no Susume

In both anime, the main protagonist has access to an armor that gives them superhuman powers to the user and enables them to battle various monster opponents. Both are dark sci-fi action-packed anime that contains a lot of blood and gore. Differences between the two is that they have different settings (Apocalypse Zero is set in a post-apocalyptic world while The Guyver is not) and Apocalypse Zero is more wacky and over the top compare to The Guyver. The Guyver also has a better story and is more serious compare to Apocalypse Zero. If you enjoy one, you may like the other as well. 

Both anime is very over the top, and both contains a lot of GAR(but Zero is more GORE, where Needless is the rather more beat the crap outta type) Also both has some ecchi moments, and the "call out your attacks" type. I say that if you liked Needless ad wanted something far more darker in its comedy, and action try Zero. n my opinion it would satisfy those who wants a lot of action in a anime then plot. 

Both have a school setting, suits that gives the wearer power, and similar antagonists. The only real difference between Kill la Kill and Kakugo no Susume is the violence. Kakugo no Susume has tons of blood/gore all over the place and is definitely not for the feint of heart. 

You watch an anime with a dark atmosphere, where awful things happen to people, an anime full of violence that is not save for kids, or adults for that matter? And for some reason you want to watch more of that? Or maybe you just want to know what else to avoid? Anyway, Wicked City (Japanese name is Youjuu Toshi) and Apocalypse Zero (Japanese name is Kakugo no Susume) are quite similar in that regard. If you want to watch something that would test your nerves, go for it. If you rather would keep your sanity, stay away. 

Two over-the-top violent and sexual OVAs set in a post-apocalyptic world where humanity struggles on despite the depravity.  

Highly violent products of their time, both are simple in nature and have nonsensical stories that often focus on shock value and unique ways of implementing gore and viscera 

Short, alternate interpretations of the future, focusing on a more apocalyptic future for humanity plagued with strange, alien-like creatures and enemies 

-Both are OVAs that are base on a bigger manga but can be enjoyed as their own thing. -Both have elements of action.  

These two ultra violent anime have a similar dark tone to them as they are both filled with extreme blood, gore and nudity. They both have characters with bio suits fighting powerful evil monsters. If you are into blood & gore, these series should be enjoyable for you.  

Two violent OVAs with deceptive aesthetics. Alien 9 looks like some sort of cute slice of life/mon show, but it ends up getting about twice as dark and weird as Neon Genesis Evangelion. Apocalypse Zero seems to be nothing but perverted grimdark ultraviolent schlock, but at heart it's an idealistic homage to Kamen Rider with black & white morality and an impossibly noble protagonist.  

If you want an extreme gore-fest with very little storyline, these two series both fit that bill. 

They're both very gory and involve quite abit of fighting. Strait Jacket is better though. 

They both contain lots of gore and violence. Both deal with school life in the cruel world, where students must fight for their lives constantly. And both of them considered to be boring and unwatchable.  

Both titles are set in a post-apocalyptic setting after the earth was destroyed by a devastating event. The main protagonist in both anime uses martial arts to kill anyone that stands in their way. They are also both action-packed anime with lots of blood and gore. The differences between the two is that Apocalypse Zero is more wacky and has mutants for enemies while the Fist of the North Star animated movie has humans for enemies and has a better story. If you enjoy one, you should like the other as well. 

Both titles are set in a post-apocalyptic setting after the earth was destroyed by a devastating event. The main protagonist in both anime uses martial arts to kill anyone that stands in their way. They are also both action-packed anime with lots of blood and gore. The differences between the two is that Apocalypse Zero is more over the top and has mutants for enemies while New Fist of the North Star has humans for enemies and has a better story. If you enjoy one, you should like the other as well. 

Both titles are set in a post-apocalyptic setting and are very similar in tone and content. They are very action-packed filled with nudity, violence and gore. In both anime, the protagonist has access to an armor that allows them to kill anyone that stands in their way. None of them are good as far as plot goes. However they can be both very entertaining to watch. If you like one, you probably will like the other as well. 

Take Apocalypse Zero, swap your super powered hero with a magical girl, and then add a sex scene, and you'll have Ryuusei Tenshi Primaveil. 

In both anime, the main protagonist gets access to armor that grants them superhuman powers and allows them to battle unique monster enemies. Both are dark sci-fi action anime with plenty of blood and gore. The only difference between the two is that they both have distinct settings (Apocalypse Zero is set in a post-apocalyptic world whereas The Guyver is not). If you like one, you should like the other. 

Both have a school setting with the main protagonist fighting against various strange opponents. Battle Royal High School is set in a non-post-apocalyptic world while Apocalypse Zero is set in a post-apocalyptic world. Both are action-packed anime filled with violence, gore, and nudity. They both have a lot of random scenes that make you go WTF at different times. If you like one, you will like the other as well. 

Dear Lord, what do we have here. Two hilariously bad titles, both which use rather, um abnormal sexual scenes for comedy; or least that's what it comes across as cause they're just that bad. Many cannot unsee moments. I really wish to say what they are, but will refrain from doing so as i wish for the shock factor to be as high as possible for you virgins. 

While these two anime have different settings, both titles has a very powerful main protagonist that fights against various powerful monster opponents. They are also both action-packed anime with lots of over the top action scenes. Differences between the two is that One Punch Man is not made to be taken seriously and is actually funny while Apocalypse Zero comes off unintentionally hilarious for trying be serious. If you enjoy one, you may like the other as well. 

Both titles have the main protagonist fighting against supernatural creatures (Highschool of Dead has zombies while Apocalypse Zero has mutant monsters). They both have a school setting and are set in a post-apocalyptic world. They are both very action-packed filled with lots of violence, gore and nudity but light on plot. Apocalypse Zero is more superhero action oriented, is more over the top and has less fan service compare to Highschool of the Dead. If you enjoy one, you may like the other as well. 

Both titles are set in a post-apocalyptic setting after the earth was destroyed by a devastating event. The main protagonist in both anime uses martial arts to kill anyone that stands in their way. They are also both action-packed anime with lots of blood and gore. The differences between the two is that Apocalypse Zero is more wacky and has mutants for enemies while Legends of the Dark King: A Fist of the North Star Story has humans for enemies and has a better plot. If you enjoy one, you should like the other as well. 

They both have a character wearing black armor that stares at the screen where you can see one eye, and both characters are named Zero. Both have a ton of fan service, although you'd have to have some weird fetishes to be attracted to any of Apocalypses.