What type of energy does a tennis ball have?

Potential Energy, it's usually a kinetic reaction.

If the ball is rolling or flying, it has kinetic energy.

If it's been squeezed, then it has elastic potential energy until it's released from the squeeze.

If it's not on the floor or the ground, then it has gravitational potential energy.

If it's still a tennis ball and hasn't been burned yet, then it has chemical energy.

If its temperature is anywhere above negative 273°C, then it has thermal energy.

It can have any one or two or three or four of these, or all of them, at the same time.