For Mario, recovering might be difficult. Don't ever use your jump immediately. Ridley's nair is amazing at gimping so it's usually better to go low right under the platform. Just be sure to not go too low, as Ridley could still gimp you there. Ridley is not afraid to go offstage, because Ridley has multiple jumps and a pretty descent recovery. As Mario, make your recovery protected by the stage as possible, if our open for too long Ridley could strike.
Mario