Indian English grammar contains many deviations from standard English forms, they are either a result of direct transfers of grammar features from native languages, of incomplete command of standard English forms, but can also be unique patterns that developed in India.
All those features of Indian English grammar will vary geographically – India IS huge and Indian people speak many different languages, besides English.
From what Wikipedia has to offer on the topic, I am going to present a few features I also treated as typical in my seminar paper some time ago: it should suffice to present the unbelievable English from the Indian subcontinent.
a) Progressive tense in stative verbs (Hindi influence): She is knowing the answer.
b) Different prepositions: to discuss about, pay attention on…
c) Use of general tag questions: You are going, isn’t it? He’s here, no?
d) Agreement with the form, not the content of a question: A. You didn’t do it? B: Yes, I didn’t.
… and many others. Generally, one could claim Indians use English the same way other speakers of English as a foreign language may do it: they adapt it to fit their native language concepts, they use the material to form new vocabulary items, they don’t bother with the official grammar etc. A Canadian and an Australian once told me they use different prepositions from Americans and the English, too, and tend to get corrected by the speakers of those two “main” Englishes.
Let me conclude the series with an Indian English expression:
Don’t worry about small-small things.