Why do you think the combined wave is more powerful than either the transverse or longitudinal wave with the same amplitude, frequency, tension, and density?

When a wave is combined, it is able to produce more disturbance if the waves are combined constructively.

A wave is a disturbance along a medium that transfers energy. Usually waves could combine with each other. This wave property is called interference.

When a wave is combined, it is able to produce more disturbance if the waves are combined constructively. This disturbance is greater than the individual disturbance produced by each wave.

Learn more about waves: link

when two waves superimposed then the resultant wave will have more energy and more intensity

It is because the resultant amplitude will be increased and given by the following equation

so here due to superposition since amplitude is increased so the energy or power of the wave will be increased

There is no effect on frequency , tension and density after superposition of waves and it will remain the same

SO energy is given as

here k = constant

A = amplitude

ice to water 1 water to vapour 2 latent heat