If the pool walls are metal and are continuous from support pole to support pole you do not have to bond everyone. Some jurisdictions only require that you bond to one of them & some want the metal wall bonded in 4 places etc...
It can depend on local requirements if there are none then I would bond to two of them and call it a day. Here is an example of one jurisdictions requirements.....
It can depend on local requirements if there are none then I would bond to two of them and call it a day. Here is an example of one jurisdictions requirements.....