Battletoads is a video game series by Rare that began in 1991, with the first game for the NES.

The game stared three anthropomorphic toads named after skin conditions, Rash, Zitz, and Pimple, and was created to rival the Teenage Mutant Ninja Turtles games.

The first game, for the NES, was known for being extremely difficult and few gamers managed to finish it without using cheats (cheat devices, like the Game Genie, were very popular at the time).
Despite its intense difficulty, Battletoads’ excellent graphics, and fun beat ‘em up gameplay, made it an instant hit and eventually a cult classic.
One feature that made Battletoads stand out from other side scrolling fighters of the time, was the exaggerated finishing moves your character would do at the end of a combo, or at other special times. This generally involved the toad’s fist or foot growing extra large for the final hit. It was cheesy but pretty cool at the time.

Battletoads could be played solo or two player coop, and coop actually made the game even harder, since you could accidentally (?) attack your friend during combat.
The first Battletoads sold very well and this spawned a series of games on a variety of consoles.

There was even a Tiger LCD game:

The series as a whole spawned seven individual releases and at its apex spawned a (poorly received) animated tv show.
A few of the more notable releases in the series, other than the original, include:
Battletoads / Double Dragon

The game featured the characters from the Double Dragon series, Billy and Jimmy Lee, and it was the first Battletoads game to feature all three toads as playable characters. The game’s engine and design was directly based upon the Battletoads series.
The NES version of the game featured 3D scrolling and fx not generally seen on the console. The Game Boy version was similar to the NES version, but only one player. The sprites were the same size although the screen was smaller (leaving less room for movement) and the 3D effects were removed.

The Sega Genesis and Super NES versions of the game are quite similar. The SNES version had better graphics and higher quality sound, while the Genesis version had more music tracks, sharper sprites for the ‘toads, and more comical reactions from the characters and from defeated enemies, as well as blood from said enemies’ post-defeat portraits.
Overall the game was well received at the time.
Battletoads in Battlemaniacs

Battletoads in Battlemaniacs followed just two Battletoads, Rash and Pimple, on a quest to stop Silas Volkmire and the evil Dark Queen from taking over the world. Many of its levels were enhanced or remixed versions of levels from the original Battletoads, and the game was highly anticipated due to the popularity of the original (and the tendency for SNES sequels to be even better than their NES counterparts).
Unlike previous entries in the Battletoads series, each character had their own combo attacks and special moves. Pimple, for example, could use the “BT Big Hammer” special move at the end of a combo, wherein an exaggerated hammer protrudes from his fists, instantly killing his foes. Rash, on the other hand, could use the classic “Big Boot Block” move from the original Battletoads, where his foot transforms into a massive, spiky boot.

While the SNES Battletoads was highly anticipated, and had great graphics for the time, it lacked the “special something” that made the original so good, despite its crushing difficulty.
Overall the game was fairly well received but could have been much better.
Battletoads 2020

Now in 2020, on August 20th to be precise, a new Battletoads game is releasing on Xbox and PC. So far it looks incredible, and with the recent killer release of Streets of Rage 4 it does show that remakes CAN be done right. Let’s cross our fingers that Battletoads continues the greatness of Streets of Rage 4.