Would this work kinda like my suggestion long ago or in a complete different way ?
Suggestion: https://forums.pokemmo.eu/index.php?/topic/51331-iv-reduce-item/#entry1080529
Edit to not use 2 post: Also if this item reduces the iv by 0-5 and for example we have a spatk of 31 and need 30 for hp grass. The item reduces it by 4 and now we have 27 spatk what is also wrong. So we would need to do this over again and in some bad cases we needed to do out of a 31 a 22 just because the item relays on pure rng. I wanna see how it goes out at the end.