Why Can't I Find Giovanni?

Unfortunately, finding Giovanni in Pokémon GO isn't something you can do whenever you want. You'll have to wait for Team GO Rocket special research tasks to appear in the game to be given the opportunity to defeat the team's leader.

Why can't I find Giovanni with super Rocket Radar?

The Super Rocket Radar doesn't immediately lead you to Giovanni; it displays locations of both decoy Grunts disguised as Giovanni and Giovanni's actual Hideout. You'll need to approach each PokéStop and investigate yourself to find where Giovanni's hiding.

How do I find Giovanni again?

In summary, to encounter Giovanni, players will need the Super Rocket Radar item, which can be made after deafeating the Team GO Rocket leaders six times. Afterwards, Giovanni will appear at the next Team GO Rocket Pokestop or in the next hot air balloon the player sees.