If you believe Adobe, there is no battery drain from using Flash on iOS devices. It’s an interesting claim, considering the onslaught of reports making the claim otherwise. But according to Adobe CTO Kevin Lynch, he cites that several studies demonstrate that perceived battery drain, is not true.
Adobe’s stance is that Apple should realize that Flash and HTML5 video can coexist. Each offers its own benefits and presents its own limitations. Despite Apple’s apparently harsh stance on Flash on their devices, Apple has opened up the option for other services to support Flash on iOS should they wish to.
As to whether or not the Adobe CTO is accurate on this, remains debatable. My advice is to try some of the apps using Flash on Android or other mobile platforms and see if you find it giving off a battery drain. While far from definitive proof of anything, it might at least allow you to determine whether or not mobile Flash is a good match for your mobile lifestyle.