Re: What would you recommend for a 3yo flooding his diapers?
As long as there are no underlying issues that may be inhibiting him from using the potty this is what I would do.
Buy a pack of pull ups and the coolest big boy underwear you can find. Maybe even let him pick it out. Set out both and let him decide what to wear. I suggest these options because paper trainers should be less appealing than cool underwear.
Also, at age three, a typical child should also be able to start learning the skill of dressing himself so why not use this as an opportunity to start learning. Continuing to diaper a three year old reduces the opportunities that he has to practice this skill. I would help out as much as needed to avoid frustration and also keep it upbeat and positive.
However, you know your child best and these are only suggestions that I would use based on the information that you provided. I know that every child learns at there own pace and if the suggestions that you get here don't work, maybe he needs a little more time. Good luck.