Genderspike is a gender in which one is normally a given gender, but very occasionally experiences sudden and short spikes of a different gender, before returning to one's normal "base" gender. The base gender can be any gender or combination of genders. The gender one spikes to can be any other gender or combination of genders, and it may or may not be the same gender every time.
Genderspike can be combined with other relevant genders. For example, a neutroisspike person is normally not neutrois, but experiences rare spikes of being neutrois.