These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Big Lipped Alligator Moment: Several sub-areas seem rather out-of-place, specifically the creepy Alien-themed area in the middle of a fairground, complete with entertaining lethal exploding alien eggs and a giant lethal monstrous swingy thingy.
In the third game, there's the oddly placed Japanese styled building that comes after a tunnel level, complete with a boss fight that looks like a samurai and he can split into two other copies. Luckily, you only fight one of them at a time.
Demonic Spiders: Those Raven kickboxers has a lot of health, can block attacks and delivers powerful kicks.
Those jetpack mooks are not much weaker than their boss version (which is by all means That One Boss for some people). Very hard to hit, hit very hard with their flying kick, superman punch, and can grab you and drop you from the sky.
Ninjas in 2 and 3. They jump around, can hit you when you are jumping, toss shurikens at you, and they can throw you For Massive Damage like bosses could. Even worse if they have swords or kunais.
Even Better Sequel: Streets of Rage 2, with better graphics, better gameplay, more characters, more enemies, more stages, more weapons...
Evil Is Sexy: If you manage to replace Mr. X as crime boss while playing as Blaze, then in her "evil ending" cutscene she qualifies as an example of this.
Axel's Grand Upper/GRAND UPPA! attack in Streets of Rage 2. Toned down in power in Streets of Rage 3. To explain a little, all characters had three specials; a standing A, forward A, and forward-forward-B. The first took off some of your energy if it hit, the second regardless of whether you hit or not, and the latter was a power attack but didn't use energy. Axel's Grand Upper was more powerful than anyone's forward-A, his own included. Axel is invincible for the entire animation (it could be used to slide straight through projectiles), it scored a hit on every single frame, hit anyone who touched Axel's sprite from any direction at any time, and slid forward until Axel hit something if he did it away from someone. About the only enemies who could deal with it were those with long counter-moves that could wait it out (so that'd be Abadede, R. Bear, and absolutely nobody else), Shiva (who had roughly the same attack with the slide run out to most of the screen) and Mr. X.
Streets of Rage 3 however has Shiva's "back attack." Unlike normal characters, he doesn't have the full range of attacks, so instead of a back attack he does a short swinging elbow to the face. This move is fast enough that you can infinitely combo it, with only the edge of the screen (or other enemies) stopping you from comboing almost any enemy to death.
Shiva as a playable character in 3. His normal moves have a lot of range and are very fast, instead of the back attack he has a 2-hit punch that can combo infinitely and his special attack takes half of one health bar and in completely invincible. It's not like he makes the game a cakewalk, but he outclasses everyone at everything.
For starters, there's those Signal dudes who are able to slide and the mooks who point their knives at you.
From the first game, the black-wearing Nora mooks. After getting hit by a punch, they'll sometimes kneel on the floor, becoming invincible and making it much harder to combo them.
In the first game, there are the kung-fu mooks who will repeatedly kick you, jump back to avoid a counter attack, waltz up and repeat. The second and third games have the blue/yellow/orange/green ninjas that will always jump around and sidestep to avoid your attacks, then they will either jump and punch you to knock you down or do a kick to knock you off your ass and throw shurikens at you. And then they become Demonic Spiders when they start to carry swords and kunais.
Those motorcycle mooks in some stages in 2 and 3. They have a habit of showing up in unexpected moments while you are running to the edge of the screen and run you over.
If any Garcias are wielding knives, they'll likely be this.
The Vices. Them holding you down for others to hit you is very annoying.
Electras are usually easy. But this changes if there are other mooks backing them up, they can easily knock you out multiple times with their electric whip and jump kick attacks while the other mooks prevent you from getting close. They also will not get back up immediately if knocked out.
The various fat enemies. They laugh tauntingly, usually after doing a full run at you that usually knocks you down. And they come in twos or have someone backing them up, and tend to run off to the sides of the screen. Later on, they bellyflop at you repeatedly. And in the original game and 3, attempting to throw them over or suplex them results in failure and life loss.
Good Bad Bugs: Max is full of them in 2, which is probably why they switched him out for Zan in 3. He slides faster than he walks, so expect expert Max players to Slide, not walk. His Thunder Tackle will DEMOLISH blocking opponents since they will take a huge amount of chip damage during his dash attack. Finally, Max's grapples work on any enemy who walks into range. This is true for all characters, but Max covers a lot of area and can jump while holding his opponent. Expect good Max players to backbreak about 4 enemies at once For Massive Damage.
Hilarious in Hindsight: Hanzou from Streets of Rage 2 first appears on a pirate ship in the amusement park. Keep in mind this is from a 1992 game.
Most Annoying Sound: In SOR2, Mr. X's "DAHAHAHAHAHAHAHA!!" every single time you get knocked down. You'll get knocked down a lot facing him. Another variant, "HUHEHEHEHEHEHEHE!" is let off by the SOR3 Bongo-type enemies and Robo-X, also when knocked down. You'll hear this a lot when Robo-X or one of his mooks knocks you down.
Most Wonderful Sound: When playing as Max, ramming your knee into the enemy's spine produces that oh-so-wonderful cracking sound.
Polished Port: The Sega Vintage Collection (developed by M2, not Backbone Entertainment) on XBLA not only compiles the entire Genesis trilogy, but also allows players access to each game from different regions, giving players the ability to play the original Japanese version of Bare Knuckle III. It also offers a slew of customization options, from video adjustments with full 1080p support to fully re-mappable control scheme. You can also save your progress at anytime, save replays, play trial modes, play online multi-player, and listen to games' soundtrack at your leisure (including the unused tracks).
Suspiciously Similar Song: SOR2's "Under Logic" bears more than a passing resemblance to The Shamen's "Move Any Mountain." Also, it is sweet as hell. The main theme (S.O.R. Super Mix) does sound much like Enigma's Sadeness.
SOR1's "Fighting In The Street" has a few elements from Technotronic's "Pump Up The Jam."
Here is a video that notes above examples and lot of others. Apparently, Black Box was a major influence on the soundtracks of the first and second games.
Also, Streets of Rage 3's Percussion sounds kinda similar to Henry Mancini's "Peter Gunn Theme".
The clawed twins in the original, Mona & Lisa, Abadede, and Shiva. Most players are guaranteed to lose at least one life against these bastards.
The clawed twins. Fighting one of them's no big deal for an experienced player: just approach them from the top or bottom of the stage, grab them and attack. Try doing that when there's another one to deal with.
Mona and Lisa in both games they appear in. They have very high evasive skills, can throw you, have jump kicks that can be quite tricky to dodge, and each of their attacks does a shitton of damage. Oh, and there's two of them.
Abadebe in the original isn't too hard, as he only has his running uppercut attack, which can be countered by either moving to the side and grabbing him, or by jump-kicking him as he charges towards you. In 2 however, he gets several new attacks, including a damaging back throw, a bellyflop attack, he can randomly break out of your combos and grapples, and his running uppercut is a lot less predictable because of all his new moves.
In 2 on Mania, Mr. X is practically impossible due to moving roughly as fast as Skate and every attack slashing away a significant part of your entire health bar.
R.Bear in stage 5 Streets of Rage 2, JUST, R.Bear. The bugger beats out pretty much ALL your attacks with his ridiculous range from his punches and his ability to counter. And you fight him AGAIN in stage 8 (as a palette swap named Bear Jr.). Granted, using a katana or a pipe makes him easier, but still.
The ninjas were already annoying in canon, here they are the bane of your existence. They get an overly long inmunity interval after being knocked down, and because they are constantly jumping, they get knocked down a lot. They also have priority over half of your movepool (even most specials!), and dangerous and damaging moves if they spawn with kunais, weapons that are basically worthless to the player.
Diesel, a trucker-like foe in the City Hall area that carries a bottle. If, when you first meet him, he throws the bottle and smashes it against your face, consider yourself very, very lucky. Outside of this extremely rare attack, his only strategy is using kicks that instantly knock you down, and the bottle he carries can be used to restore his health if he keeps drinking from it. Just to spite you further, if he gets knocked off screen, he will drink while off screen so you can't hit him! Oh, and he never drops the bottle until you kill him, which then causes the bottle to shatter.
Special Effect Failure: Some soundtracks skip a little before entering the main loop, particularly glaring in Never Return Alive.
Stop Helping Me!: Playing with an AI partner will invoke this, especially if their setting is set on aggressive. If you have an enemy in your grasp and you start to combo them, your partner may decide to wander into the fray and and try to help out by attacking your target, which will usually break your hold on the enemy and wind up doing less damage than you had intended. If friendly fire is turned on, this will just get worse.
Version 4 introduced Super Shiva, who, along with palette swaps of some earlier bosses, had to be beaten within a certain time limit. If the time runs out? No retries, no continues, Bad Ending, smashed keyboard. Version 5 excised him, although another path you can take in the game, based off of Streets of Rage 3's bomb situation from Stage 6, has you fight SOR3 Shiva, who is even MORE aggravating than SOR2 Shiva, whom Super Shiva was a sprite edit of. Super Shiva was also playable in version 4, and was quite the Game Breaker (he had a Hadoken, for God's sake).
Rudra. Moves extremely fast, throws ninja stars to attack from a distance, can hit you several times in place, and lands on her feet if you toss her backwards. Once her life bar is down to half, she'll start creating illusions of herself where they all can do the same attacks but die in a single hit. Oh and every time she sends out the clones, they all come crashing down, hitting you every time unless you can see when they are going to appear and either dodge or use a special attack to cut through the attack. When Rudra's life bar is nearly gone, the clones increase in numbers and THEY EXPLODE when killed.
That One Level: The upper path of the jungle in level 6. Its longer than the entire level up to this point (the other path just ends at a boss), and it's plagued with kickboxers and ninjas. The final part of this level is at the bottom of a cascade with knee-deep water that slows you down, but that doesn't seem to concern the increasingly large waves of ninjas. To top it off, try defeating Onihime and Yasha when you can only run as fast as a pregnant sow.
They Changed It, Now It Sucks: Some fans have expressed disappointment over how SOR3's levels have been implemented in the remake, as they were scattered over several paths instead of having their own straight one, like those for 1 and 2. Thankfully there is a mod you can install for the Sor Maker, that let's you play through the SOR3 stages as they were in SOR3.