Dolphin allows you to "side-load" an old, vulnerable version of Flash Player, which isn't a good choice from a security perspective.
Puffin is the only decent solution I know about at this point. It processes Flash Player on a server in the cloud, and streams the output back to your phone. This insulates you from malware you might pick up running the old Android version.
I'm not an Android user (no tablet or phone) so I can't make any endorsements that would hold any credibility, but most of the Flash solutions I've read point to Dolphin as the best alternative.