There are many kinds of Englishes spoken around the world, both as a first and second language and the term 'Englishes' suggests this. One view holds that these are equally correct and valid. This lessens the importance of a 'standard' English, and questions giving priority to 'British' or 'American' English as targets for teaching English.
A learner in India who is not planning to travel to another English-speaking country but who needs to transact business in India might need to be taught Indian English.
In the classroom
The experience of many teachers is that learners know very clearly what kind of English they want to learn. It is important to identify needs and not make assumptions about what they are.