You must target two creatures as you cast Fulgent Distraction. If you can't (because there's just one creature on the battlefield, perhaps), you can't cast the spell.

Fulgent Distraction can target tapped and/or unequipped creatures.

If one of the targeted creatures is an illegal target by the time Fulgent Distraction resolves, that creature won't become tapped and no Equipment will be unattached from it. The other creature will still be affected. If both of the targeted creatures are illegal targets by the time Fulgent Distraction resolves, the spell is countered.