I'm assuming you're talking about SH approaches rather than falling opponents. Those two opponents are possibly the toughest aerialists to handle.(aside from ground game of course) Their moves have great range and priority and they have awesome edgeguarding ability. Really the only thing you can do is try and space yourself and throw pikmin, and then go on the offensive when they land. Like DDD and GaW, I've had a lot of experience with Zelda, another great aerialist. She outprioritizes Olimar in the air(if she can sweetspot) and it's hard to stop her from lightning kicking you when you're both airborne. Try to wade it out, and punish any mistakes they make. Look for opportunities to grab them while they land. It's near unavoidable. Take for example, a DDD that'll float above you and bait you into using an empty upsmash. Try rolling under him and wait for him to land, and wait and shield any attempt at an attack to knock you back. Punish the lag on his moves and wait for him to land. Hope this helped a little. good luck.