∠G , ∠H , ∠K
∠G and ∠H are congruent as they have same shape and size. Their angle measure and length is same. Either of the shape is reflected over the x-axis. ∠K is congruent with the shape, due to same angle measure and is enlarged over the y-axis.
∠M is not congruent, it does not have similar shape. Their angle differs.