Poll Everywhere has always played nice with PowerPoint. Now it also plays nice with Google Slides. By installing the Chrome extension "Poll Everywhere," you will find an extra menu item at the top that says "Poll Everywhere" whenever you open Google Slides. You can them click this menu item and begin creating polls in the Google Slides.
Remember that your students can work in Google slides too as it's a great collaborative tool. You can have as many as 50 people working in a Google Slide set at one time (that number may change in the future).
See the screenshots below showing installation of the Chrome extension and where it can be found one you open Google Slides! Click screenshots to enlarge.