This my answer to that question that I gave recently.
I feel that Pilates is a lot like Yoga as far as getting certified is concerned. They are both very deep movement programs and require a solid and comprehensive study program. I can’t see how weekend cert programs and online programs could prepare an instructor properly. I would find a program nearby that is very indepth with a well trained instructor who has a verifiable background working with a well known Pilates Master. If you don’t have access to such a program nearby, I would consider going to a specialized school for an extended vacation. It may be pricey, but you owe it to yourself and your future students.