>>54274860Home Tracker ID. Either they had Pokemon that could only get to SV from Home and had no Home Tracker ID, or they edited immutable values of a Pokemon with a Home Tracker ID and the heck check compared their game's copy of the Pokemon to the backup in Home and saw differences. Honestly, both of these are easy fixes. Change immutable stats before uploading to Home, or, if they already have a tracker, zero it out and reupload them so they're assigned a new one. The only real question left is "what happens if you upload a Pokemon from a game it's not supposed to be in?", like if you zeroed out an Ursaluna in SV, then tried to upload it.
