Does google still penalize you for onclick popunders?

Does google penalize you for having onclick pop-unders? I don't know what other ad types I can use without penalizing my rankings

Penalize probably not but user experience will be worse and your bounce rate will increase. On top of that, some websites that use Popups are flagged by Chrome with "This site shows intrusive or misleading ads.".

Unless you're running like a streaming/porn site, I'd avoid popups or at least just bind them to specific Elements on the site (eg. a video player).

Google's mobile interstitial penalty mechanism is designed to punish intrusive ads that disrupt the user experience, especially on mobile devices. Although interstitials are less offensive than pop-ups, they are still considered intrusive ads if clicking on a pop-up ad has the following conditions.