Is it true that when you have braces, there is a possiblity that you'll have malocclusion?

Malocclusion is why: Malocclusion is latin for "bad bite". If the teeth do not fit together ideally and they are not lined up correctly, then that is call a malocclusion. Malocclusion is what orthodontists treat. After braces the malocclusion no longer exists and a good occlusion (or bite) is what one has.

Malocclusion: A malocclusion is a bad bite. Orthodontists strive to correct malocclusions by moving teeth into their ideal position or as close to that as possible. General dentists who think they perform orthodontics as well as orthodontists without the same formal training often fall short with their results. Patients who try to save money with orthodontic "bargains" may end up with a malocclusion.

Inverse: Orthodontic treatment (including but not limited to braces) resolves malocclusion(bad bite). In the hands of a skilled orthodontic specialist there should be no malocclusion after treatment. Seek treatment with the most competent specialist you can find.

Braces will fix: the whole idea of braces is to correct any malocclusion you may have. Your teeth and bite may not be perfect during treatment, but by the time the braces come off, you should expect to have a great smile and a perfect bite