Correct pronunciation

I am a pre-service teacher. In the future, I have to teach my students the correct pronunciation of words. I have known that there is no such thing as a correct accent or a good accent since every accent is supposed to have an equal status. However, when I teach, it is very likely that I have to use a dictionary and the recordings that correctly pronounce words. In most of the dictionaries, General American and British accent's pronunciation will be provided, which are commonly considered to be the 'correct' pronunciation. The IPA symbols of a word are mostly based on the two accents. Also, I was told that the pronunciation from the IPA is the correct one and I am supposed to stick to them when teaching. Then, the problem appears. Wouldn't the two accents be considered as the only correct versions? There are a lot of English-speaking countries in the world, but people in which speaks with different accents. Does it mean they are wrong or deviated from the correct pronunciation?

For example, in New Zealand, people often pronounce 'mate' as 'migh' (might without the 't' sound). Does it mean that they pronounce it wrong? I know my question is pretty awkward. But I am really struggling to figure out what a correct pronunciation is. Does 'correct pronunciation' really exist? Allow me to change the question a bit: Is there an 'accentless pronunciation' in the world?

My dilemma is
If there is such a thing as correct pronunciation, a lot of other versions like Aus English or NZ English would be considered to be out of standard.
If there is none, every people in many countries could claim that they have no problem with their pronunciation, including people in China, India or even North Korea.