It only works for SOME versions of Sm4shIf powersaves works by dumping and restoring only encrypted images, then yes that'd be the case. However, doesn't it support cheating for games like Sm4sh and similar? Because that would imply being able to decrypt newer games, including SMD.
I can edit with a screenshot of the error if you want
Powersaves SORTA lets you do this. You CAN NOT just plug a save into PKHeX then restore it with edits.You can gen/edit pokemon with with a Powersaves iirc.
I don't remember the entire process tho, but I do know you can't PKHeX a Powersave backup then restore it