I am currently creating an interactive pdf that will be used primarily online and across various mobile devices. I have tested what I have so far on my phone, which is android powered, and on an ipad. The ipad opened the document but didn't perform any functions until it was brought into ibooks. Once it was there, everything worked except the text fields; they weren't recognized at all. The phone couldn't open it at all. I doubt anyone will be looking at the document on a phone, but I want to ensure all bases are covered. What can I do to ensure that text fields as well as any other interactive elements will be usable on mobile devices?
What kind of interactivity are you expecting? There are many kinds: Forms, buttons, video/audio, etc.
When you are viewing interactive PDF, many of the PDF readers on mobile are very immature and don't support all features: