Play instead gameboy, gbc, gamegear, atari lynx, and stuff like that on handheld.
NES and PCE should work okay too, at least my DS Lite had no problems emulating them. But here the problem is the screen is too small, with sprites, text, and games designed for regular size TV.
Otherwise if you really *have* to play SNES on portable system, just build your own with an ARM SBC, screen, battery, enclosure, and other parts you chose yourself. Then at least you can pick hardware and not pay Nintendo or someone else lotsa money and still be stuck with a shitty mess of stuff to work around.