Why do riku and mickey join the organization is it so they can protect roxas until hes exsictince is returned to get Sora back and is the orginzation bad or good you mean there nobodys and nobodys r

Riku and Mickey don't join the organization, they just have the outfits. Riku is even referred to as "the Organization Imposter" in 356/2 Days. I'm not sure why they have them.

The organization is considered bad because they're destroying worlds to reach their goal (Kingdom Hearts). Nobodys are made at the same time when a person becomes a heartless if their heart is strong.