Question

she overcome her fear of public speaking if she wants to be a good debeater (can/could)

Answer 1

she could overcome her fear of public speaking if she wants to be a good debator

Answer 2

The answer is

She can overcome her fear of speaking if she wants to be a good debeater.

》》 we should not use "Could " in the sentence. because the sentence is in present tense .so for present tense we have to use can.

:-)hope it helps u.