A tetrahedron.
Tetrahedron
It depends on which method of tag you are playing
a base
Tetrahedron
pyramid .
A tetrahedron.
Tetrahedron
A polyhedron has only polygonal faces and any one of them can be considered a base. Therefore a polyhedron with 0 bases cannot exist.
It is a pentagon.
It is a pentagon.
A cone.
It depends on which method of tag you are playing
This is a "trigonal pyramid" or "tetrahedron."
That seems to fit the description of a pyramid
No, it cannot.
a base