Now Google decided to show warnings next to search results that use a lot of Flash content, but only for iOS and Android 4.1+ devices. "Starting today, we will indicate to searchers when our algorithms detect pages that may not work on their devices. For example, Adobe Flash is not supported on iOS devices or on Android versions 4.1 and higher, and a page whose contents are mostly Flash may be noted like this:"
The warning says: "Uses Flash. May not work on your device." You can tap "try anyway" or "learn more". The reason? "A common annoyance for web users is when websites require browser technologies that are not supported by their device. When users access such pages, they may see nothing but a blank space or miss out a large portion of the page's contents."
Google recommends developers to create modern multi-device websites using HTML5. For example, Google's Web Starter Kit is a simple framework that supports the Web Fundamentals best practices out of the box.