I've made many Senshi Fuku over the years. Here are the methods I have used
1) Full bodysuit with removable skirt/collar/bows
2)Full zippered dress with skirt and collar attached as well as panty part of bodysuit being attached
3) Full dress with separate bodysuit bottoms. I ended using Spankies for that. Spankies are cheerleader briefs, not to be confused with Spanx, the things people wear when they don't feel like exercising.
4)All item components are removable/detachable. This is the most practical for washing purposes, especially if you have custom dyed your fabric and are concerned about color bleed out.
I hope that helps. Feel free to PM me if you have any more questions