I am the father of a 10 yr. old boy who wants to come and live with me and his mother won't let him. His mother and I were divorced and custody decided in Ohio, but she has since moved to Florida 2 yrs. Ago. I know that in Ohio there is no legal age that a child can decide which parent he wants to live with, but if I file custody papers will the court listen to his wishes, or would I just be spending a lot of money, only to lose anyway?

At 10 its unlikely they will give much weight to his preference. So you would have to have a greater reason then just that he wants to.

Did she have your permission to move?

Minors don't get to decide in any state. Many a child has an argument with one parent and the absent parent suddenly seems better, only to regret it, but that's beside the point - a child can't make the decision. You might want to file for visitation, say a week twice a year and 2 weeks the next year, or a month in the summer.

In the US, there is no state that allows the child to decide, no idea where that myth ever came from. He has to be 18 to live where he wants

As for as testifying in court, the judge may listen to him but the main thing will still be the evidence that you present, why would it be better for him to live with you.