Originally Posted by Oracle

Ice Climbers were powerful because they had great range and damage combined with their decent mobility and brutal grabs. Gimmicks don't put somebody in the top tiers, they can accent certain base features, but they aren't strong enough to move up in tier lists. Some examples would be Luigi's insane wavedashing in Melee, or Kirby's b being capable of a guaranteed kill if they break out when you've fallen off the ledge facing away from it; they were gimmicks that gave them some surprise factor, but they were just showy, the actual characters had either little or nothing working for them.