I want my opponent to follow the ball but what happens is one ball get destroyed and a new ball is emitted from the block. And the opponent doesn’t follow the new ball

The emitted object is a different object, so your enemy isn’t going to follow a different object.
Instead of destroy and emit, try teleporting the ball with Position.
(in) number (X) position
(in) number (Y) position

It will probably be easiest to give the ball a once to 2 extractors, one for x and one for y. They connect to the (set) of the corresponding numbers.