I've got a few pointers for you if you are frusterated with Oli's recovery.
1. If your knocked offstage, whatever you do, DO NOT DOUBLE JUMP UNTIL YOUR ARE RIGHT BY THE STAGE. I cannot stress this enough, as it means the difference between life and death, trust me.
2. An important thing to know: Olimar can only tether 3 times before he must again place his feet on solid ground; after that, death. So NEVER ledge camp with U-B without climbing back onto the stage, you will die.
3. Because Olimar is gimpable, using him to stageguard offstage aggressivly (what I do) throws most players off. They aren't expecting anything but fear from you off of the ledge: take advantage of their folly. If you play it right, Olimar is a grinding machine of death on and off of the stage, intimidating and unpredictable--perfect :D.
4. U-air is a crucial move to remember when faced with an edgehog. If you are close enough to them, they will be forced to relinquish their position, giving you the opportunity to tether back and continue the fight.
5. Finally, this should go for ANY character, but ESPECIALLY with Olimar: KEEP YOUR COOL OFFSTAGE. Always analyze the possibilities, don't waste that double jump, and if you cant get back on, save the tether, aim carefully, and try to stagespike their camping *** ftw.
I guess this sort of turned into general advice for olimar, but I'd hate to see an Olimainer shy away from such an awesome character because he is discouraged. Good luck and I hope I helped!