That would depend on the game you're playing however if you're playing FireRed and LeafGreen he will have Pokemon such as Onix, Rhyhorn, Kangaskhan, Nidorino, Nidoqueen, Dugtrio and Nidoking and for Pokemon such as Nidorino, Nidoking and Nidioqueen you can use Psychic-type Pokemon in order to beat them, Rhyhorn and Onix you can use Grass-type Pokemon in order to beat them, Dugtrio you can use Flying-types in order to beat it and you can use Fighting-type Pokemon in order to beat Kangaskhan.
The serious last time you beat Giovanni is at the viridian city Pokemon gym.
beat blaine at cinnibar and then Giovanni at viridian city.
Earthquake (TM26) is your reward after you beat Giovanni
Go to saffron city and go through the silph co building and beat Giovanni again then go to the gym to get your 6th badge.
Use any POKEMON that is effective against GROUND type
You will encounter team rocket after you beat giovanni, but you will never encounter giovanni in the game again.
To the neighbourhood
The serious last time you beat Giovanni is at the viridian city Pokemon gym.
After you beat Giovanni in Pokémon Red, Blue and Yellow he goes to the gym in Viridian City. He is the final gym leader.
As the gym leader, Giovanni is supposed to be the eighth of them. So you have to beat the other seven before you can get to him.
beat blaine at cinnibar and then Giovanni at viridian city.
nowhere
when you beat Giovanni in the game corner
you must beat the other 7 gyms
You have 2 beat the elite 4 in Saffron City............ when you have beaten them you face your rival on the floor where you get 2 beat Giovanni... horrayyy you beat your rival...then beat Giovanni .... Afterwards.. you c the owner of sliph co. he gives you the master ball...
Earthquake (TM26) is your reward after you beat Giovanni
Beat Giovanni at viridian city's gym.