Support for double strike resolutions and other resolutions was added to the development tree a couple weeks ago, and will be in the next big release. If you want to try it out now, you can compile a build yourself.Hi:
The Retroarch supports 240p output signal like as FCEUGX and others wii emulators?
This option is called original in FCEUGX and also known as double strike in Wii Mednafen...240p native support for the wii is fantastic for me who likes to play in OLD CRT tubes and is what made me choose it...
Some initial testing shows results that are very similar to the actual systems. Example:
Normal RetroArch resolution (480i) - http://i.imgur.com/wE28H.png
224 double-strike resolution - http://i.imgur.com/ZWBDW.png
Actual SNES - http://i.imgur.com/HX7SQ.png