Reliable Asian university rankings datasets suitable for evaluating applications to a graduate program
I believe that using university ranking as a criteria for admission is fundamentally unethical. 

Extremely good students end up going to middling or poor undergraduate institutions for any number of reasons. To downgrade somebody's application just because they went to a mediocre institution is actively going against the academic ideal that merit should be able to rise, and even poor institutions generally have at least a few students of excellent potential.  Complementarily, pedigree is no guarantee of quality: rubbish students graduate from elite institutions all the time.

Now, there is, of course, a strong correlation between the quality of an institution and the quality of the students that it produces, and there are, of course, basic matters of accreditation: nobody should respect a degree from Trinity Southern University.  In general, however, you should judge the students and not the institutions.

So, how do you judge a student from Asia? The same way that you judge a student from an unfamiliar university in Europe or North America, by the accomplishments for which they can give evidence.  To judge classwork, one of the methods is to ask which textbooks were used (this is what some MIT departments do).  To judge other work, look for the concrete products, such as research papers, code or web pages online, etc.

Students from universities you do not know will still be at a disadvantage, and doubly so for students from a very different environment and who may lack English communication skills, such as will often be the case for many Asian universities.  But you can at least take steps to not prejudice yourself unduly by sorting their universities by their ability to game semi-arbitrary ranking systems.