A rectangle or, if the squares are allowed to overlap it is possible to have a 16-gon ("star" shaped), 14-gon, 9-gon, 8-gon.
There are quite a few. Circles, squares, triangles...
a rectangle
A prism.
Squares.
rectangle
A triangular prism
Rectangular prism
A cuboid or a rectangular prism.
If the squares can be placed on top of one another, they could form a shape with from 6 to 16 sides.If the squares can be placed on top of one another, they could form a shape with from 6 to 16 sides.If the squares can be placed on top of one another, they could form a shape with from 6 to 16 sides.If the squares can be placed on top of one another, they could form a shape with from 6 to 16 sides.
There is no solid shape with exactly four squares and no other faces.
An isosceles-triangle based prism.
You need 4 rectangles and two squares * * * * * No, you do not need to have squares: there can be six rectangles - as in a brick shape.