Mario has shown that the two triangles are congruent. Three transformations are not always necessary when moving one triangle on top of the other.
The SSS (Side-Side-Side) congruence theorem states that if three sides of one triangle are congruent to three sides of another triangle, then the two triangles are congruent. Mario's sequence of transformations (translation and rotation) resulted in overlapping triangles, which demonstrates congruence without the necessity of completing a reflection. Therefore, he has correctly shown congruence through his transformations.