Nike (NKE 0.31%) is the largest activewear company in the world by far, but many smaller competitors have been gaining ground in taking it on. Lululemon Athletica (LULU +4.92%) was one of the original competitors that created a niche in the space, capturing market share and forever changing standard casual wear, but it's also struggling today. Nike is a powerhouse that's one of the largest apparel companies in the world of any kind, not just athletic wear. It has the highest brand power of any apparel brand ...