Unova's Blessing can grant Self Polymorph with no forms

When using Unova's Blessing, a spell or special can be replaced with Self Polymorph. When you learn Self Polymorph this way, you don't learn any forms to polymorph into.

Casting Self Polymorph brings up the usual menu to ask what you want to polymorph into, but the menu is empty. The only option is to hit Backspace to cancel the menu.

If you later learn a Self Polymorph form, the menu functions normally.