What are some of the top bands/songs played in the nightclubs in Italy?

In good nightclubs in Italy you hear what i think is usualy for any other country clubs: David guetta, Bob Sinclair, Avicii, Katy Perry etc.

if you go to clubs for older people there are sometimes live bands that play italian folk music, like Raffaella Carra; ricchi e poveri, Celentano etc

I don't know about nightclubs, but I can tell you what's on the radio - American music. Either American music right out or performed by Italian people, often in English. One of my cousins is a musician and I talked to him about it, that the Italian music business, and Italian musicians, suffer because everyone wants to listen to American music. Sure, there is Italian music and Italian music stations on the radio, but largely it's like being in Los Angeles.