Adolf Hitler is the only character to have something horrible happen to him at the end of the video. Three times. Whether or not you think he raps better than Vader, he's Adolf Hitler and Vader is allowed to kill him at the end of every video because he's that evil.
Public opinions on Thomas Jefferson and Thomas Edison have both taken a beating since people have become more and more aware of their uglier actions and choices (though many historians disagree with the way these two have been presented in popular culture lately, with many still defending their reputations). Both were given opponents designed to knock them down a peg. While Edison vs Tesla started out fairly egalitarian until Tesla eviscerates him in the last stanza, Jefferson vs Frederick Douglass is an utter bloodbath. Jefferson is forced to use his entire second verse to answer Douglass about his participation in slavery. It may be worth noting that Hamilton, the cultural phenomenon also involving history and rap music, criticizes Jefferson very harshly on the same subject.
Donald Trump gets torn to shreds in his rap battle against Hillary Clinton. By Abraham Lincoln, mind you, as Hillary herself isn't put in the best light either.
Bill Nye. Nice Guy who spends half his verse praising his opponent, or a Bitch in Sheep's Clothing who uses compliments to segue into cheap shots on Newton's personal life?
The Easter Bunny. A wimp who foolishly picked a fight with a killer, and spent his second verse begging for mercy? Or a Badass Pacifist who spent his second verse expressing disgust at Genghis Khan's brutality?
Frederick the Great's death. It's not hard to look at it as an attempted 'fuck you' to Ivan, robbing him of doing the deed himself.
Ash Ketchum. Did he go too far with his line about Darwin's children, or was it standard fare for the rap battles and he just had a really good, if dark, ending line?
Anvilicious: Several battles in Season 5 tackle political issues that, at least at the time, were very topical in America — namely, Jefferson vs Douglass, Banner vs Jenner, and Trump vs Hillary. These battles were criticized for their very heavy-handed messages ("Racism is bad", "Transphobia is bad", "Donald Trump is bad"), which many viewers found obvious and/or severely liberal-biased.
Awesome Ego: It would be easier to note those who don't show this. After all, each rapper either brags about their achievements, ridicules the opponent's achievements, or simply references events they were a part of - and you know each one of them can back up their claims.
Chuck Norris. His fans love his portrayal in the series, but a number of other people don't really like the Memetic Badass jokes that comprise most of his rap.
Frederick Douglass either "exposed Jefferson's hypocrisy of owning slaves while trying to end slavery" or "failed to show that he accomplished anything other than learning to read and write".
Caitlyn Jenner. Whether you think positively or negatively of her depends on your opinion of the real Jenner (which there is justification for either way). The fact that she got nearly three times as many lines as the Hulk did adds to her controversy; some say she deserved the extra spotlight and/or that the Hulk isn't known for being a big talker anyway, while others still consider it pretty unfair.
Ash Ketchum, for being a pop culture icon pitted against historical figure Charles Darwin and supposedly having no connection to him. Arguments are breaking out in the comments with people complaining about the above, while others defend him and explain the connection. Particularly odd is how this is far from the first time ERB has used a loose connection and/or pop culture versus actual history; see Franchise Original Sin below.
There's a division between fans who want to see more "Adolf Hitler vs. Darth Vader" matches, and fans who think those battles are getting stale and the focus of the show should be placed elsewhere. The latter was acknowledged in "Hitler vs. Vader 3" in the form of an included comment.
"Batman vs. Sherlock Holmes" is very polarizing; half the fans like it just fine, the other half are put off by the delivery of Batman's verses, on top of Batman having very few good lines.note Many not knowing that Batman in ERB is more of a shout out to Badman as portrayed by Pete Holmes of CollegeHumor, which is a rather brutal (but affectionate) parody of Batman.
Reception to "Miley Cyrus vs Joan of Arc" was pretty divided: while some people are fine with it, it has a share of detractors who think it's one of the worst battles. There are also fans who are disappointed at the match-up and wish Joan had gotten a different opponent.
Invoked with the mention of the Affordable Care Act in ERB News 3.5. The hosts are well aware that it will be very divisive, describing it as "Polarizing News."
Theodore Roosevelt: Some people will hate it. (clip of Lincoln smacking Obama) Some people will love it. (clip of Lincoln smacking Romney)I! Don't! Give A! Damn!
While most fans are otherwise fine, some fans are split about Goku vs Superman...mainly because how Goku is played byRay William Johnson, who is pretty disliked by more elite YouTube enthusiasts.
Many people found "Stephen King vs. Edgar Allan Poe" either unfair because Stephen King had a longer second verse, or fair because Poe's really fast rapping compensated for it.
"Artists vs. Turtles" caused a bit of division between people who loved it, and people who thought that it was good but weak compared to other season finales. The fact that Season 4 started with an even bigger battle suggests that Epic Lloyd and Nice Peter could have done a better job.
The first two battles of Season 4's second half ("Lewis and Clark vs. Bill and Ted", "Harry Houdini vs. David Copperfield"). Some call the battles "brilliant", and others find them lackadaisical and missing the spark that made the series so great to begin with. The two sides do not get along.
James Bond vs. Austin Powers had varied reception, with some thinking the battle should have been Daniel Craig's Bond vs. Sean Connery's Bond from the beginning, and some thinking that Austin Powers shouldn't have been pushed to the side halfway through.
Douglass vs Jefferson also got this, with some claiming that Douglass pulled the race card to win and never actually countered Jefferson's question of "The fuck did you do?", while others felt that Douglass made multiple fair points. The fact that Jefferson was forced by the writers to spend his entire second verse countering the slavery accusations (Which is more the writers insulting a man for living by the standards of his time, and was something that was absent when Washington was in a Rap Battle) was also poorly received by some.
However, there's a growing number of fans that counter that Thomas Jefferson wasn't "defending" himself for an entire verse, but rather that he was condescending to Frederick Douglass: more specifically, he's talking down to Douglass instead of apologizing. (The last line "So forgive me! I was busy, I had a lot to do. But we did it, you're free now so...we cool?" is used to further this point.) Because of this, there's an Alternate Character Interpretation going on that the writers weren't just turning Jefferson into a weak-willed strawman.
Bruce Banner vs. Bruce Jenner is one of the most divisive battles in the show's history, with by far the highest dislike percentage. This is due to the presence of Caitlyn Jenner (see Base-Breaking Character above), as well as how one-sided it becomes in the second half note Jenner gets almost three times the number of lines Hulk does. Then there's the debate over whether Banner should've had a different opponent; one side dislikes the reasoning behind the matchup (simply the fact that they're both named Bruce and that they have a second form to them that changes radically who they were) and often brings up Henry Jekyll as a better choice, while the other side says that Jenner deserved a voice and/or that Jekyll would have been too obvious. And that's before getting into the political side of things, with some people accusing the battle of being transphobic, others calling it too "politically correct," and still others who think the first two groups are making mountains out of molehills.
Ivan the Terrible vs. Alexander the Great also has varied reception. Some thinks that the battle should have kept Alexander and Frederick the Great alive at least until the end of the battle for them to have an all out brawl with Catherine the Great and Ivan while others think that is just too many characters and the former two would end up doing nothing anyway and/or that Catherine's rap and Alexander's / Frederick's historical accurate death was awesome enough to compensate for their send off. Most of them agree that Pompey the Great is completely wasted, though (see below).
Donald Trump vs Hillary Clinton. Apart from the obvious, Lincoln explicitly telling Hillary to 'beat this dummy' and a call-back to Obama vs Romney, where Lincoln slaps Trump... and then slaps him again have caused a lot of controversy.
Voltaire rhyming Frank with Frank is painful but doing it four times straight is hilarious.
Trump in "Donald Trump vs Hillary Clinton" goes full-on Politically Incorrect Villain, boasting of how he plans to rid America of latinos and make Mexico pay for everything. It's so over the top dickish that it crosses into hilarious. Then he crosses right around into terrifying when you realize ERB based all his lyrics on things he's actually said. Which makes it crossing the line three times in an ERB first!
Designated Villain: Their historical battles suffer at times from lopsidedness, where one side is portrayed in a manner that is historically fair while the other side uses Hollywood History.
A good example is George Washington vs. William Wallace. Washington is portrayed with ugly teeth (which he did have), is called out as a hypocrite for owning slaves while William Wallace is shown as Mel Gibson's Braveheart which gave him a Historical Hero Upgrade. The real Wallace was a feudal lord and a warrior who would certainly not suffer republicanism of any kind and degree. This prevents the battle from being a fair fight since Washington can't fully attack Wallace and call him out for hisHypocrisy or reminding him that Robert the Bruce was the real Braveheart.
Rasputin vs. Joseph Stalin has a little of this going on. While Stalin was, well... a horrible person, the battle takes a turn out of its usual format and gives five characters one verse each before the fact that Rasputin wasn't exactly a non-controversial guy either can be unpacked, making his first verse a little of a case of the pot calling the kettle an asshole and getting a pass on it.
Ivan the Terrible vs Alexander the Great(and other greats like Catherine, Pompey and Frederick) portrays Ivan IV as being intrinsically worse than the others which a cursory glance through their biographies would find highly generous to the latter group, with Catherine the Great shown more positively than Ivan IV. Catherine dismisses the horse story as BS as the only character in the battle who gets a rebuttal verse, while Ivan IV is not allowed to challenge the similarly bogus claim by Frederick and others that he murdered the builders of St. Basil's Cathedral by plucking out their eyes, or defend his Accidental Murder of his son, or his positive achievements, merely being a left a caricature.
Downplayed with Donald Trump in Trump vs Hillary. Sure, Lincoln blasts his ass while Clinton gets off relatively scot-free note getting called out on having a creepy smile or being full of 'blah blah blah' hardly counts, but he gets a chance to present a full well-written verse and point out the things Hillary did wrong. It's closer to Tesla vs Edison than to Banner vs Jenner or Jefferson vs Douglass. Of course, most of the statements he says in his verse were based on actual things he said.
Boba Fett. He only appears for eight seconds and gets killed by Hitler of all people, but his lines were so awesome that he's become very popular, with people pleading for him to return. Interestingly enough, he was voiced by Ray William Johnson, a particularly divisive YouTube personality, which shows how much people liked the character. To the point where he got his own bonus episode during the season 4-5 hiatus.
Nikola Tesla. His battle with Thomas Edison was one of the most requested rap battles up until they fought. He also is one of the few battlers to be overwhelmingly considered by fans to have curb stomped his opponent.
Edward Kenway. His cameo in "Blackbeard vs. Al Capone" was so popular, there is a huge, increasing number of fans begging for him to have his own battle.
Raphael and Michelangelo (the artists) are quite popular thanks to being played by Smosh.
Lump the wiener dog appeared in the "Bob Ross vs. Pablo Picasso" battle for all but 1 second, but he's one of the most popular cameos in the ERB series. His wiki page has 92 comments, showing that this minor character had sparked more discussion than many of the actual rappers (including the "stars" of the battle he appeared in — Bob Ross and Pablo Picasso — themselves).
Cast-wise, Xin Wuku's stunts get a lot of love.
Sacagawea has been called the best part of "Lewis and Clark vs Bill and Ted", mainly for much of her cameo consisting of her beating up a bear in the background.
Bruce Banner/The Hulk. Even though his battle was very one-sided in favor of Bruce/Caitlyn Jenner, the vast majority of voters on both the Wiki and the forum consider him the winner.
From "Alexander the Great vs Ivan the Terrible", Frederick the Great proved very popular despite getting the least amount of lines of all the main rappers. It helped that he got his own unique beat, and an awesome one at that.
Also from "Alexander vs Ivan", Pompey the Great got a lot of love due to being a Butt Monkey who only had one line in the battle, leading many fans to view him as a tragically wasted character.
Juliet from "Bonnie and Clyde vs. Romeo and Juliet" battle on Tumblr.
When Theodore Roosevelt got his battle, this was bound to happen with his weird facial expressions and his over-the-top delivery.
Franchise Original Sin: Ash Ketchum vs Charles Darwin sparked many arguments and hate comments saying there was "no connection" between the two, and/or getting mad at ERB for using a nerdy pop culture icon up against an actual historical figure. The "no connection" argument, while even still technically untrue as both Ash and Darwin study their respective world's animals (and are acquainted with "evolution"), easily applies as well to many older battles that based themselves off of just having similar names (Ghostbusters vs Mythbusters) or general occupations (Gordon Ramsay vs Julia Child), if even that (Genghis Khan vs Easter Bunny). And plenty of pop culture icons that fall within nerd-dom have shown up battling historical figures before (Artists vs TMNT and Lewis and Clark vs Bill and Ted). Plus, both of these complaints were prominent in the second season's far better received Wright Brothers vs Mario Brothers.
Randy Savage died about 4 months after "Hulk Hogan and Randy Savage vs. Kim Jong-Il" was released. Then Kim Jong-Il passed away in December (though Kim could be considered an Acceptable Target, much like Hitler). They later added a brief annotation honoring Randy Savage's memory. Kim Jong-Il? Meh, who cares.
In-universe, Ben Franklin jokes that the battle's going to mark the Death of a Salesman. Just after he starts his second verse, Billy Mays kicks the bucket.
Putin's verse is incredibly upbeat and optimistic, which may be connected to the fact that the battle was supposedly requested by Putin himself. However, since the battle release, he has outlawed homosexuality and invaded Ukraine. The fact that he has the last verse (meaning nobody can call him out) also makes it harder to watch.
Growing the Beard: When the series started, the costumes and special effects were cheaply-done, the lyrics lacked complexity, and most of the rappers didn't even have a very good sense of rhythm. By the end of Season 1, all of these things had been significantly polished, and the beginning of Season 2 kicked it up another notch. The iconic "Bill Gates vs. Steve Jobs" battle set the standard of great-looking production values and intelligent and innovative rapping which the rest of the series continues to hold (and improve).
The former mentions how "the Four will always be Fantastic". The Fantastic Four reboot, which premiered a few days after the battle, turned out to be disappointing. Of course, this could instead be Hilarious in Hindsight depending on your viewpoint. It could even be Heartwarming in Hindsight, if one retroactively takes it to mean that the 2015 film's existence does not mean the Fantastic Four are Ruined Forever.
Henson's line about how the Hulk will always be incredible becomes a bit cringe-worthy considering how the later rap battle with the Hulk himself ended up being one of the most divisive in the series, with the highest dislike percentage out of all the raps. It could also be seen as Hilarious in Hindsight considering that many viewers of that battle thought the Hulk won — he was, indeed, still incredible.
In a similar line to the above, the "RoboCop vs. Terminator" battle referenced the disappointment that was Terminator 3, and said battle ended with an ad for Terminator Genisys, released around the time of the release of the video, complete with a brief cameo by Arnold himself. Then the critical and box office results of Genisys came in and, well, let's just say that it seems that Terminator 3 will have to share its place as most disappointing Terminator movie.
The reference to Steve likely refers to the fundamentalist/anti-gay slogan "Adam and Eve, not Adam and Steve".
Freddie Mercury mixes this with Foe Yay in his final line to Sinatra.
Hypocritical Fandom: Occasionally, fans will call out certain insults as "going too far" and going so far as to say the character lost because of using them; for example, when Cleopatra and Ash Ketchum taunted their opponents, Marilyn Monroe and Charles Darwin respectively, about their kids dying (Marilyn through miscarriages, Darwin through diseases). Even though plenty of insults in the past have been used that are just as bad, if not worse, and have been supported or even considered to be so amazing they pulled victory for the person who used them (for example, Julia Child remarking on Gordon Ramsay being an abused child, and Caesar threatening to beat and enslave Shaka Zulu). There's also the obvious fact that there's no such thing as going too far in a rap battle to begin with.
A minor example, but ERB caught quite a bit of flak for tipping over the piano in "Bieber vs. Beethoven", even after explaining that it wasn't working. The amount of work that goes into creating an instrument like a piano, much of which is impossible to do with a machine and requires intense hand labor, causes many people to treat them as works of art unto themselves, and destroying one is considered a major offense to music lovers.
Season 5's "Thomas Jefferson vs Frederick Douglass" is fairly contentious, as it talks about slavery, which is best left at that.
The decision to start making censored versions of episodes. It received mass backlash when the first censored episode (of the above episode, no less) was released on the main channel, with complaints consisting of the idea being cheap and pointless as well as the censorship being poor. The creators responded to one such comment explaining that the purpose of the censored versions was to make them safe to watch in environments such as schools, and as of now these censored versions are being uploaded to the side channel to slightly less uproar.
Season 5's "Bruce Banner vs Bruce Jenner" is very contentious, as it features the polarizing figure of Caitlyn Jenner and has her sex change compared to turning into the Hulk. Also, trans issues aside, many just don't think it was a good matchup for the Hulk and think Jenner's longer verses overshadowed him (in the latter half Hulk gets 8 lines versus Jenner's 22).
Season 5's "Donald Trump vs. Hillary Clinton" evoked lots of complaints of the battle being one-sided and biased towards Hillary, even with some of the nastier shots Trump had in his verses. Even when Abraham Lincoln showed up, he mainly trashed Trump and only insulted Hillary for her creepy smile. In "Obama vs. Romney", he ends by smacking both candidates "as equals"; in the new episode, he just smacks Trump twice. This led to some cries of "Where's the gender equality?". Others point out that when Abraham smacks Trump once it's funny, when he smacks him twice it's hilarious.
Iron Woobie: It's subtle, but Vladimir Lenin apparently watched his most trusted student dismantle his efforts toward a socialist paradise in favor of a brutal dictatorship. The reason you don't notice is that Lenin vents about this with authority.
A common complaint on "Artists vs. Turtles" is that it's too short for an 8-person battle, and that the Turtles' verses are half as long as the Artists.
The rap part of "David Copperfield vs. Harry Houdini" lasts less than a hundred seconds, with just two relatively short verses for each rapper, which is disappointing coming off the mid-season hiatus.
Averted with "Shaka Zulu vs Julius Caesar" which, despite being relatively short (especially after the much longer "Philosophers" battle), was met with overwhelmingly positive reception.
For one specific part of an episode being this trope, a lot of people were displeased at the "Bruce Banner vs. Bruce Jenner" fight since Hulk barely has any lines while Jenner is allowed to ramble on and on.
Go on almost any YouTube vid of the Stay Puft Marshmallow Man these days, and there's bound to be at least a few comments quoting Stay Puft's "I live so large, you can't harsh my mellow". Which'll usually followed by another comment quoting the next line, "Just one step took me out the ghetto".
Most Annoying Sound: A bizarre example as it doesn't come from the Epic Rap Battles at all. After "Bill Gates vs Steve Jobs" battle came out, many fans went looking for an instrumental version of the beat used, only to quickly grow tired of the original's use of "Tristan on the track" as a refrain. Tellingly, numerous versions now exist on YouTube, editing it out.
In the Making Of video for "Elvis vs. Michael Jackson", there is a clip of Epic Lloyd spitting out half-eaten bananas into a trash can. He doesn't like bananas too much.
George Washington's teeth can get a bit distracting due to this.
Never Live It Down: Because Cleopatra gets in three lines attacking Marilyn Monroe for being promiscuous, detractors may claim that every single woman vs. woman battle consists entirely of both sides calling each other sluts.
Older Than They Think: There's a small group who considers Rhett & Link's Epic Rap Battles to be ripoffs of these; their first Epic Rap Battle (the straight-up match between the two) predates "John Lennon vs Bill O Reilly".note Nevermind that the two pairs are on pretty good terms with each other, and that Rhett and Link appeared in "Mario Brothers vs Wright Brothers", "Artists vs. Turtles", and "Lewis & Clark vs Bill & Ted", while Peter and Lloyd made a cameo in R&L's Epic Rap Battle of Manliness.
The folks who complained about Bruce Jenner's Sailor Moon-style transition into Caitlyn Jenner probably never heard of the Sailor Stars.
Trump supporters have also accused ERB of a recent liberal bias after his rap battle with Hillary Clinton, ignoring that in the past they've made fun of other conservative figures like Sarah Palin, Mitt Romney, and (most frequently in the early years) John Mc Cain. Not to mention considering their support for gay rights and feminism, ERB has been pretty front and center with what politics they support.
Boba Fett appears for all of maybe eight seconds in the season 3 premiere. The half-verse that he does manage to get is awesome.
Pompey the Great didn't even get to start his verse due to being decapitated with about five seconds of screentime, and yet many people jokingly determined him the winner of the battle. It helps that his appearance is some historically accurate black comedy.
Painful Rhyme: Given that this is a series based on rapping, these were inevitable. All examples are listed on the trope page itself.
Rescued from the Scrappy Heap: Ray William Johnson is a fairly divisive YouTube creator, to say the least. However, he was able to stand his ground as an actor for the show, with many people considering his eight-second Boba Fett performance to be the best part of the third "Adolf Hitler vs Darth Vader" match, and a number of people considering his raps as Goku to be better than Superman's in the eponymous "Goku vs Superman".
In season 5, the excellent portrayal and characterization of Julia Child and Catherine the Great finally made the fanbase amends with the ERB team for their previous lackluster female / male vs. female battles and/or accusation that almost every female characters appeared has elements of Slut-Shaming in their verse.
Rewatch Bonus: Thanks to the show's use of fast-paced rap music and chroma keyed visuals, just about every episode has at least one cleverlyric or Funny Background Event that you're guaranteed to miss on the first viewing, unless you have extremely quick comprehension skills.
Sarah Palin is generally considered to be the winner of the battle "Sarah Palin vs Lady Gaga" despite being incredibly transphobic as most people considered her to be hilarious due to how many times she Crosses the Line Twice.
Columbus is also generally considered to have won in "Columbus vs. Kirk" due to many people finding their imitation of William Shatner's speaking style extremely annoying to listen to.
In the second "Adolf Hitler vs Darth Vader" battle, many people like Hitler better, even though he's definitely the more evil of the two. Of course, if you're on Vader's side, you're still rooting for the empire.
Genghis Khan is almost unanimously agreed to have won in "Genghis Khan vs. Easter Bunny".
A fair few people thought The Stay Puft Marshmallow Man won in "Ghostbusters vs. Mythbusters".
In "Jim Henson vs. Stan Lee", the winner is generally considered to have been Walt Disney.
Most viewers thought that the Terminator beat Robocop.
Quite a few viewers sided with Donald Trump in his battle against Hillary Clinton. Even Abe Lincoln couldn't sway them.
Rule of Cool: The foundation of the whole series. You have far-flung historical characters that know enough about each other for a rap battle. They are even fictional characters rapping against real people; dead or alive. It doesn't make any sense but it sure is cool.
Thing One and Thing Two aren't popular with the general public because of how Ax-Crazy they act toward Shakespeare as well their bad lines that only consist of violent threats with no variety.
Mr. T has the third-lowest vote count on the official ERB website, and it's almost certainly due not only to his comparatively-weak raps, but also to the misfortune of having to throw insults against Mr. Rogers. And if there's one thing to learn from the Internet, it's that you do NOT insult Mr. Rogers.
If one had seen the original Robocop films, it could be a subtle shout-out to how ED-209 is painfully "animated" in several of it's appearances in the franchise.
The scene of Bill Nye walking into frame as he says "And I'm still in my prime" doesn't start offscreen, meaning he literally just blinks into existence rather than walking into frame.
From the same battle, in his title card, when Bill runs across the screen holding a beaker, his shadow is very short and a bit deformed.
Not so much "special effects" as "camera zoom", but still counts: when Juliet stabs herself, because the camera isn't zoomed in enough, it's very obvious she just thrust the knife beside herself and was nowhere close to her chest. Said knife also completely disappears in the shot where she's on the ground dead.
Parodied in "Superman vs. Goku", as Superman spontaneously grows a gigantic third arm just for the sake of punching Goku as he's dissing the Off Model animation of Goku's series.
When Walt Disney draws the Mickey Mouse logo, the sparkles he creates... really don't come very close to following the outline made by his finger.
Any time a small version of a character is shown to be standing on something (Stephen King having two small versions of himself on his hands, Isaac Newton on a book Bill Nye is holding, etc.), it's very likely that they'll look to be standing somewhat off of it, or just otherwise not standing in a realistic way.
During the Deadpool vs Boba Fett bonus battle, Boba Fett's jetpack tends to disappear from his body when he's doing certain dance moves. These are most notable when Boba's in the background dancing while in the foreground he's rapping. In his last verse its even worse, as it disappears from the one in the foreground when he spins around then reappears after he finishes.
When Frederick Douglass flips a coin in his battle against Thomas Jefferson, it's absolutely painful to watch it land - the heads side of the coin obviously changes, making it very obvious that the flipping was a separate animation that somehow they didn't consider altering to be consistent with the coin in Frederick's hand.
Audio effect rather than visual, but Steadman's line at the end of "Oprah vs. Ellen" is so obviously Autotuned it's cringe-worthy.
In a wide shot, Julia Child sets a dogfish on her cutting board. It then cuts to a close-up where she appears to be hacking at it with her cleaver, but when we return to the wide shot, the fish is clearly undamaged.
"Stan Lee vs. Jim Henson". The video's length is 5:32, making it the longest ERB episode for its time. So when Lee and Henson stop battling and make peace only 2 minutes in, you just know a third rapper is about to enter.
Also subverted later in the episode. If you're expecting the battle to continue after Disney's verse, forget about it — the remaining 2 minutes and 10 seconds are spent on the end slate.
A similar situation arises in "Alexander the Great vs. Ivan the Terrible" when Ivan kills Alexander and seemingly wins the battle... less than halfway through the video. And again when Frederick the Great dies and there are still two minutes to go.
Fans complained that the rap of Frederick Douglass and Walt Disney are more about what both of them represents (slavery in Douglass's case and corporation and copyright in Disney's) to the detriment of informing the audience about their accomplishment / character and they ended up being Flanderized.
One particularly common complaint is that Hulk didn't get enough lines in "Bruce Jenner vs. Bruce Banner". As mentioned above, Jenner got nearly three times the number of lines Hulk did.
Pompey the Great, who only got one sentence before being unceremoniously killed off by Catherine the Great.
"George Washington vs William Wallace" was considered by some to be extremely underwhelming, especially coming after the excellent string of battles that was "Goku vs Superman", "Edgar Allan Poe vs Stephen King", and "Isaac Newton vs Bill Nye".
Season 3 in general compared to season 2. A common complaint is that few of the songs are memorable.
"Lewis & Clark vs. Bill & Ted" had the bad luck to come out after the hiatus that occurred after the director battle royale, and then over the next few weeks was overshadowed by progressively better battles.
"Stan Lee vs. Jim Henson". Not only did it come on the heels of "East vs. West Philosophers" and "Shaka Zulu vs. Julius Caesar", both of which got very positive reception, but it served as the finale for Season 4—an honor that many people thought would go to "Philosophers". This set the bar high for the battle... only for the titular characters to get roughly one verse each of actual battle rapping note Stan gets an additional half-verse before patching things up and being friendly. And then Walt Disney enters and turns the rest of the battle into just a Boastful Rap about himself and how he now owns the creations of both competitors. It hurts that the battle's flow is rather slow and the lyrics aren't particularly memorable; people seem to like the concept but not the execution, and consider it a good battle but far from a good season finale.
Uncanny Valley: The brief zoom-in on Ash Ketchum's eye in "Ash Ketchum vs. Charles Darwin" where it changes from live-action to his familiar anime style. Thankfully, it goes back to live-action soon afterwards, but the transition still looked weird.
Unconventional Learning Experience: The amount of detail weaved into the verses and visuals of a battle can surprise listeners, especially when it comes to actual historical figures. In fact, many rap battles can make people want to go out and learn about people like Newton, William Wallace, Gandhi, Da Vinci, etc, etc.
Season 5 in general has visual effects that are more cinematic than the previous seasons (the tree branch scene in "J. R. R. Tolkien vs. George R.R. Martin", the Blue Team scene in "Gordon Ramsay vs. Julia Child" and Bruce Bannerís transformation are examples), but "James Bond vs. Austin Powers" takes the cake. Bond's first verse is comparable to the stunning visuals of James Bond movie openings (complete with a Bond Gun Barrel), Austin's verse is also an eye-pleaser, and Sean Connery's Bond comes by to top it off.
The fandom was displeased with the unannounced hiatus that happened after the "Bill Gates vs Steve Jobs", some even going so far as to thinking that the work would become an Orphaned Series. Cue the announcement that the next six Rap Battles would be uploaded back-to-back every fortnight, followed by a holiday break and more episodes. This was impeded only by a small Schedule Slip in regards to "Batman vs Sherlock Holmes".
It happened between Seasons 3 and 4. Many fans found "Artists vs Turtles" to be an incredibly disappointing finale to the third season, but were immensely pleased when Season 4 came back with "Ghostbusters vs. Mythbusters", which they considered a group battle done right.
When season 4.5 came around, many fans found the first two battles lackluster and began accusing Peter and Lloyd of selling out and not having fun anymore. Then along came "Terminator vs Robocop", which silenced some dissenters, and then "Philosophers East vs West", which was met with a great deal of praise.
After three controversial battles in a row in Season 5, the mid-season finale "Alexander the Great vs. Ivan the Terrible" was very popular again.
Season 5 was accused of having numerous battles that didn't make sense and/or were too heavily weighted in one side's favor. Then Tony Hawk vs. Wayne Gretzky finally got back to a sensible and balanced match.
The Easter Bunny really bit off more than he could chew.
Freddie Mercury starts off as one. He spends most of Frank Sinatra's first verse and part of his first verse moping at his piano, saying that he's heard all the insults that Frank hurled at him before. Then he gets going.