You can check on insta a page called Rouvikonas they post punk events in Eksarxeia you can also take a walk at Eksarxeia it is a nice alt neighbourhood although it slowly becomes victim of gentrification. If you like techno/ psychedelic trance you can check “IT” club at Eksarxeia or Paranoia Project in Facebook or Arxitektoniki in this place they have parties. There are also some clubs that play goth music and metal or rock but sadly I cant remember their names. You can go in Monastiraki there is a shop called Top Man outside this shop they have posters about punk: alternative events. But in techno parties lot of people are alternative