Gauss’s law cannot be used to find electric field strength near an electric dipole near a triangle with point charges at its corners, this is because

These systems do not have spherical symmetry .Hence Gauss’s law cannot be valid

The charge configuration of these systems do not pass adequate symmetry. Hence, Gauss’s law is valid, but it not practically useful .             

Systems do not have cylindrical symmetry .Hence Gauss’s law cannot valid

Gauss’s law does not apply in case of point charges