Which villainous team is led by Giovanni in the Pokémon games?

The villainous team led by Giovanni in the Pokémon games is Team Rocket.

Team Rocket is a criminal organization first introduced in Pokémon Red, Green, and Blue. Its members steal Pokémon, conduct illegal experiments, and pursue profit and power. Giovanni serves as its boss and is also the Gym Leader of Viridian City in the original games.

Giovanni disappears after his defeat in the first-generation storyline, and Team Rocket is said to disband in Pokémon Gold, Silver, and Crystal. The group later returns in Pokémon HeartGold and SoulSilver, while an alternate version called Team Rainbow Rocket appears in Pokémon Ultra Sun and Ultra Moon.

A common mix-up is confusing Team Rocket with the villainous groups from later generations: Team Aqua and Team Magma operate in Hoenn, while Team Galactic operates in Sinnoh. Giovanni also leads Team GO Rocket in Pokémon Go, a related but differently named incarnation.