Giovanni is the leader of Team Rocket, Pokemon's first evil team. Team Rocket is a criminal organisation dedicated to the kidnapping and sale of pokemon for profit, among other things which differ depending on the canon. Their motto explains their goals pretty well:
"Steal Pokémon for profit. Exploit Pokémon for profit. All Pokémon exist for the glory of Team Rocket."As the leader of Team Rocket, Giovanni obviously oversees its operations until he either disbands the organisation for good (rby) or exiles himself to return another day (frlg/hgss). Other than being the leader of Team Rocket, he was also the Gym Leader of Viridian City until his defeat at the hands of Red/Leaf. He gifts the player the Earth Badge and a TM (Fissure-gen 1, Earthquake-gens 3/7) after losing. In the Pokemon Adventures manga (Pokespe for short), he instead goes into hiding on two occasions, eventually re-taking control of Team Rocket both times. He also has the greater goal of world domination, much like his anime counterpart, and is responsible for the creation of Mewtwo. However, he was also behind Deoxy's creation, and by extentsion the meteor that threatened to destroy Hoenn in the Delta Episode of ORAS.
