Here is the sheet which gives the number of unique colleges above every rank.
Here are links to selection critera for all the regional sites:
Amritapuri selection criteria https://icpc.amrita.ac.in/2019/onsite-contest/
Kanpur selection criteria http://kanpur.indiaicpc.in/PrelimRules.pdf
Kharagpur’s selection criteria http://acm.iitkgp.ac.in/ under Contest rules.