Bubblestrat

It still works. I know for a fact that there's a combination that works well. But I can't share it because it may benefit the spoofers on this site.
And the site's Bubblestrat Calculator works well.

10-12 cp Gastly with Lick (attacker) versus 22-25 cp Gastly with Astonish (defense).

Astonish strat

I think Bubblestrat variations/alternatives still exist.

Recently, I witnessed a Valor team (spoofers) in my area building a level 10 gym in 10' with 3 Magikarps CP ranging from 24-28, then they put all Blissies in that gym.

When I travelled to the countryside a while back, I also found 2 other Valors gyms with 2 Magikarps CP 25-28 at the bottom and the rest was Blissies.

In this update, Voltswitch has the longest CD time, then Confusion and Splash have the same CD time. If Confusion works, then Spash works as well. But I haven't found out how exactly they did it.