Quick and Easy Questions (please read the OP)

[Trixie]

See, the presence of a Key-blade "auto-summons"  Heartless, because they seek to destroy the bearer of the Keyblade, as it is the one weapon that can destroy them. As a result of this, I am curious if such would be allowed, or not?  If not, I'll have to rethink my opening plans for Repliku.

You can have it summon Heartless as just part of the storyline. It doesn't need to be inherently built into the Keyblade move itself. Or it can be fodder. However, if you were to weaponize the Heartless or if they were to be used in combat then it would add to the cost of the Keyblade or require an assist/a purchase to be made viable.

EDIT: Like Future Warrior stated. Lore discrepancies aside, your options are still the same.