I think these would be my choices:
1.
Bar-headed goose - A widely-kept species in captivity that is, to my mind, the most attractive of the geese, found in a wide range of biomes across Asia and is suitable for walkthrough enclosures, simple pond displays and mixed enclosures with species like Indian rhinoceros.
2.
Blackbuck - One of the most commonly-kept antelope in captivity that has a striking appearance, is able to be kept in mixed enclosures with Indian rhinos and bar-headed geese and is even kept in walkthrough enclosures here in Europe.
3.
Indian crested porcupine - One of the most commonly-kept porcupine species in captivity, with a broad range of biomes (definitely desert, grassland, temperate and tropical) and occurring across a variety of different regions in Asia.
4.
Lion-tailed macaque - An endangered species of monkey that would probably serve as the flagship species of the pack, with a fairly good showing in captivity and endemic to the rainforests of southwest India, an area otherwise unrepresented in the pack.
5.
Rusty-spotted cat - All of the cats we have in Planet Zoo are among the top ten biggest species, so I'm choosing the complete opposite - this is one of the smallest cat species (about the same size as a meerkat), that is becoming increasingly common in zoos.
6.
Striped hyena - An attractive species of large carnivore that includes Asia and Africa within its range, is pretty common in captivity and is sufficiently different in appearance, behaviour and requirements to the spotted hyena to warrant inclusion.
7.
Yellow-throated marten - The largest and most colourful of the martens, which lives in social groups and would add the first species of climbing mustelid to Planet Zoo, which would go well with the climbing otters and burrowing badger.
Exhibit.
Spotted pond turtle - Personally, I would prefer an African cobra species and I always think of leopard geckos as being a pet shop species rather than a zoo animal, so I have chosen this endangered and very pretty freshwater turtle as my choice for an Indian exhibit animal.
There are plenty of other options I considered as well, like the Indian giant flying squirrel (as big as a cat that I think could use a tweaked version of the jumping animations when climbing in order to glide), Asiatic lion (just so that we get a better-looking lion), pygmy hog or Himalayan monal.