Do both husband and wife need individual $25,000 in a Thai bank for a retirement visa?

As i already mentioned is just happening. To many people have no clue about what you ask and start telling you requirements of the Non Immigrant O visa based on being over 50 years of age, the Extension of Stay based on being over 50 years of age and it is waiting for the next with requirements of the Non Immigrant O-A visa or O-X visa. I do not see the need to explain all the differences as you did not even decided yet to spent long time inside Thailand. Having long time stay inside Thailand needs bank account, address etc. Please do some research and good luck in the country of your choice.

yes and a seperate account each.

Where do you like to apply and where are you? If in Thailand what kind of visa do you have now? 4 different visa and the Extension of Stay are all called retirement visa, nice short populair name, but a very wild guess to give the correct requirements.