I found a glitch involving the clone on GameFAQs https://gamefaqs.gamespot.com/gba/589485-shining-soul-ii/cheats

and noticed nobody seems to be using it. I have validated its existence on both the JP cart and the English cart. Using this ive been able to power wine to any stat i want, come into the clone room, throw a healing item as he runs towards me, move down and ensure the item is gone (was used by the clone) and then turn around and one shot him.

In addition ive tried throwing a number of other items to see if it has any effect but nothing yet, wings, soul, mp items, bombs. Only healing items seem to be do anything leading me to believe that this may be intended rather than a glitch.