The Ice Climber SlowFX glitch is a glitch performable only in Super Smash Bros. Brawl. The glitch occurs after the activation of another character's Final Smash; even if it never actually connects with the Ice Climbers themselves. Once the Final Smash is complete, either Nana's or Popo's (Whichever the computer's controlling) special effects (such as landing dust and hit sparks) will be slowed down, as if they're under the effect of the Timer item.
The effects end when one or both of the Ice Climbers are KOed.