I have tried everything on pond apple and I can tell you that it is not the rootstock you want for Atemoya.
Perhaps for Cherilata but certainly not for atemoya.
You go to is Cherimoya as was previously noted. Some people have also recorded some success with soursop though I have not had much luck with it.
If you have pond apple that you wish to graft to, then I suggest you get Cherilata or soursop scions. You may also get some Cherimoya scions if you wish to use them as interstock to graft your atemoya on to. I had some success with a couple of Cherimoya varieties on pond apple and then I grafted atemoya on to the cherimoya.
If you are going to buy seed to grow rootstock, just get cherimoya.
By the way, there is this old post though it has not been kept current, I have found it useful.
https://tropicalfruitforum.com/index.php?topic=16673.msg213803#msg213803