While I do not like talking here, I must clarify things for you.
Both of you are thinking of the wrong item.
Nightshroud, the item you wish to use is Armor Clash, however that is unavailable, and you cannot de-digivolve an [A] digimon.
Quote:
5. De-Digivolve!
Description
sad Down grades your digimon to its next lower form)
*Can only be purchased 1 time per digimon.
*When you use this, you cannot anymore digivolve your digimon in any way.
Cost:1000 TP for [M]
Cost:1150 TP for
Cost:1250 TP for [C]
Cost:1750 TP for [R]
Cost:2250 TP for [T]
Digimon Partner Required:Any digimon except [A] and [H] Ichigo, there is an item called Burst Digivolve, you do not need Mode Change, that is for changing it back, not to the digimon.
I will make Ichigo's art after he edits the order to the correct item, while Nightshroud you are going to have to wait.