Adobe dropped supporting Flash for ALL mobile devices four years ago. Flash is a security risk even for supported platforms so using it intentionally is in essence inviting your phone/tablet to be compromised. Dolphin relies on an outdated Flash plugin so it's a) not going to be usable on some sites anyway and b) not safe regardless. You might want to look into the Puffin browser app, it doesn't 'infect' your mobile device with a browser plugin like Dolphin does but instead relies on a more current version of Flash in its own online servers.
But again, Flash itself simply isn't safe.