The whole series is strictly arcade.
Crime Fighters (1989):
Button 1: Punch/Pick up weapons/Use weapons
Button 2: Kick
At the right distance, your strike combos will change. You'll sometimes throw enemies with 1, or grab their face and continue to drive your knee into it with 2. 1 & 2 simultaneously is a jumping knee, however pressing forward & 1 & 2 simultaneously does a spin kick. You can kick enemies while they're down, strictly with 2.
This gets odd with the differences between the 4 and 2 player cabinet. Unfortunately, neither allows you to choose your character. The 2 player cabinet adds a 3rd button, for a back kick. Your health is represented by 4 squares, and you have 2 lives per credit. In the 4 player cabinet, your health is represented by numbers, which can be increased by adding more coins. You also gain some after boss battles.
You need to be really precise with some moves. To be honest, hit detection can be pretty poor, especially for the minimal reach of some weapons, which are instantly removed from the field if you get hit once.
The game has some surprisingly cartoony TMNT-like moments, considering the more serious, overall Double Dragon-like approach of it. Sometimes bosses have ways of leaving themselves wide open to your attacks as well.
This is the first beat 'em up in which Konami got the idea to attack enemies while they're on the ground, which would be a defining feature of this series.
Vendetta/Crime Fighters 2 (1991):
1-4 players (the 4 player cabinet forces the character onto the specific coin slot, whereas the 2 player cabinet allows players to choose their characters)
"Vendetta" is also the title of a different beat 'em up on the Commodore 64, Amstrad CPC, and ZX Spectrum.
Button 1: Punch/Pick up items/Use weapons
Button 2: Kick
Pressing 1 while really close will either grab an enemy or throw them(seems you're more likely to grab if you're not holding a direction), except in Hawk's case, he'll headbutt enemies for an instant knockdown, if he doesn't throw them. If you grab with the other 3 characters, either button will strike, and away & either button will throw. Forward & 2 while close will grab an enemy for some knee lifts with either button, or throwing with away & either button. You attack enemies on the ground by pressing 2 when near them, but if you're holding a chain, you can wail on them with it, pressing 1. This time, if you're knocked to the ground, on your back, you can kick with either button for as long as you're lying down. 1 & 2 simultaneously for a special attack, and forward & 1 & 2 simultaneously for a leaping special attack, no risk to health.
Some enemies can grab you from behind, either button will attack them. Unlike Crime Fighters, there are health restoration items(food, of course). Like Crime Fighters, some bosses will leave themselves wide open to attack.
You have 4 playable characters. Blood, a former boxer, Hawk, a former pro wrestler(obvious Hulk Hogan knock off), Boomer, a martial artist, and Sledge, an ex-military convict.
Violent Storm (1993):
1-3 players (Adjusted in the Tab button dip switch setting in MAME. Even in 3 player mode, the players can still select their characters)
There's actually no real evidence that this game relates to the other 2, other than being developed by Konami, and being able to attack fallen enemies. It's often just lumped in with the other 2 games, in spite of not being called Crime Fighters 3 in Japan.
Button 1: Attack/pick up item
Button 2: Jump
Away & 1 will attack behind the players character. Low attack with Down/forward & 1. Dash attack with Down/forward & 2(can be cancelled into a jump, and anything that can be done while jumping). Wade has an uppercut with Up & 1. With Kyle, the player can rapidly press 1 for a rapdid multi-kick attack. Fallen enemies can be further attacked with 1(even with a weapon in hand), or picked up into a grapple with Up & 1. 2, 1 jump attacks. 2, Down and 1 dive attacks. Forward & 2, 1 does a forward jumping attack, while forward & 2, away & 1 does a different forward moving jumping attack. All the directional jumping attacks can be cancelled into each other. Everyone can wall jump by pressing forward & 2 toward a wall, then 2 again as they touch the wall(actual wall, not the edge of the screen). This will automatically perform the forward & 2, 1 jump attack, but can be cancelled into the away & 1, or Down & 1 attacks. Walk into an enemy to grab them. From a grab, you can strike 3 times with 1, throw forward or back with Left/Right & 1, alternatively throw enemies behind you with Down & 1(except Boris, who will slam them into the ground), or do that same last throw forward(again, except Boris for obvious reasons) with Down/forward & 1. Boris also has an Up & 1 grab move. During a grab still, he can also press 2, 1 for a backbreaker, 2, Up & 1 for an atomic drop, or 2 and any other direction for a powerbomb. 1 & 2 simultaneously is everyones desperation attack.
Honestly, if you didn't know any better, you'd swear this was one of Capcoms. It even has the character tropes that Capcom started with Final Fight: Average(Wade), strong(Boris), and fast(Kyle). One interesting aspect is that Wade and Kyle can't throw large enemies, which isn't often seen in beat 'em ups outside of the Streets of Rage series.
It's a unique series in that none of the games in it feel like any of the others. Even if Violent Storm isn't considered a part of it, Vendetta still feels wildly different from Crime Fighters.