Fan Translation: Made in Wario) is a series of games featuring the Nintendo character Wario. The franchise was created in 2003 with the release of Mega Microgame$! for the Game Boy Advance. While the first two games were developed by Nintendo R&D1, subsequent games have been co-developed by Intelligent Systems.
The original Japanese title of the series was Made in Wario, but outside Japan it's WarioWare.
Pyoro, which was the inspiration in story for Wario starting up his own company, was a mini game in every single game in the WarioWare series, and then ended up published standalone by Nintendo for DSiWare under the name Bird & Beans. Paper Plane (retitled Paper Airplane Chase) is possibly the same way.
The original WarioWare was based on the microgames present in the 64DD game Mario Artist: Polygon Studio; some of the microgames in Polygon Studio even received straight ports in WarioWare!
Game & Wario was not originally meant to be part of the series, as explained in its promotional Iwata Asks interview. It was first designed as several generic tech demos pre-installed on the Wii U before being retooled as a new IP featuring expended version of said tech demos. Difficulties linking the minigames together in a coherent storyline lead to the development team scrapping the original framing device and use the WarioWare characters.
The main cast of Warioware is often called The Warioware Crew by some fans.
It seems the commercial failure of Game & Wario has pretty much put the series on ice, with cameos from the characters being the only thing out of the series since. This, combined with the poor sales of Wario Land: Shake It! a few years earlier, has left Wario without a dedicated series of his own for the time being.
Twisted! never reached European shores. The reason for this was never explained, but it certainly wasn't to do with the illegality of mercury tilt switches in the EU — Twisted! uses a piezoelectric gyroscope instead. Fortunately, the GBA is region free, so anyone in the region who knows English can play the game via importing. And as a result, the Mona Pizza song is unobtainable for European players as well (until Brawl for the song, but it was remixed), because to hear it you need to either play Twisted, or at least have a game cart to use alongside Touched! via the GBA slot in the DS console.
Twisted! was released after Touched! in North America (which is even weirder because Twisted was supposed to be 18-Volt's intended debut in the series, which presents a bigger problem since Twisted was in Development Hell until June, and 18-Volt had one repeated line), and not at all in Europe.
Ashley's song in reverse supposedly states she has taken kids to Hell. In reality, this was just a Mondegreen of the snippets of the song skipping backwards.
It's commonly said that Ashley is a little kid in Japan but a teen internationally. That's not true. Her age is ambiguous in Japan.
As mentioned, Game & Wario was not originally a Warioware game.