2 pairs of equal angles
8
A regular hexagon has six equal internal angles of 120 degrees. None of them are right-angles !
4 such as a square
8 if it's an regular octagon
Whether it is a regular or irregular octagon does not matter. An octagon is, by definition, a 2-dimensional figure with eight sides, and therefore with eight angles. A regular octagon will have eight equal angles and an irregular octagon will have eight angles some of which are not equal to the others.
There is only one regular quadrilateral, the square. A regular polygon must have equal sides and equal angles, and in the case of quadrilaterals that is a square.
In a regular nonagon there are 9, if its irregular its dependant.
A heptagon has seven sides. In a regular heptagon all of the sides and angles are equal. In an irregular heptagon the sides and angles are not all equal.
An equilateral triangle, has 3 equal sides and 3 equal angles. However, in a regular equilateral triangles, none of these angles are right angles (90 degrees), they are all 60 degrees.
As many sides as you like providing that it has 3 or more equal sides and equal interior angles
6 A Regular Hexagon has six sides of equal length, and 6 equal angles.
A regular 5 sided pentagon has 5 equal interior obtuse angles of 108 degrees