Sidearming overstable discs you should be releasing the disk level or with with an anhyzer where your disc is higher than your elbow. These would be firebird, banshee, whippet, xcaliber, boss, flick, force, venom, predator.
Sidearming understable discs you should be releasing level and get it to roll, or release with a good bit of hyzer angle with the disc lower than your elbow and getting it to either flip and fly straight, or it will turn left and fly depending on how understable and your angle of release. These would be valkyrie, sidewinder, roadrunner, monarch, beast, archangel, dragon, XS, XL, spectra.
My 174g glow dx teebird is very understable(Teebirds are typically a fairly stable disc, just not this one for some reason) for me, so I have to use it as a roller or put a lot of hyzer on it. The Pulse is a pretty sweet sidearm disc you may want to check out and it was designed to be the perfect sidearm disc.