Well, judging by the characters under your name, I'll assume you play Cloud? Unfortunately, you're kinda SOL if that's the case. As someone who plays a lot of Ridley, my two favorite characters to gimp in the entire game happen to be Cloud and Chrom due to their terrible recoveries. My only advice would be to keep your limit gage as close to full as possible at all times. That way, if you get knocked off stage, it should top off your gage and let you limit climhazard up from under the stream of fire balls. As a general trick, use the "brawl" airdodge (without directional input) to pass through the stream and reduce the lag you would suffer afterward. The ideal scenario would be: You jump back toward the stage, Ridley shoots the fire balls, using the momentum of your jump, you airdodge through the stream to reach below the ledge, then up B to safety. This can apply to most characters with limited recovery. If you happen to play someone with amazing recovery (like Greninja or Pikachu) then simply launch yourself over Ridley's head while he's puking fire balls. That's one reason why I love Greninja: his recovery options are insane. He can shadow sneak through the fire balls to kick Ridley in the face (or reverse edge guard him from behind), hydro pump over him, or even use Substitute to simply take the shots and then teleport up high.
