is there any sure shot possibility that every student applying for special rounds will be admitted to one or the other colleges?

Nope there are no such sure shot possibilities that anyone applying for special rounds will get seat. See the special rounds are conducted to fill up the vacant seats. So through the counselling cell, the number of vacant seats available will be filled up from the special rounds. But yeah! sometimes students gets lucky and they get seats as many mid rankers don't apply for special rounds.  SO yeah! if luck is good then many times moderate rankers gets good seats but its not certain.

I hope this answer helps. All the very best for your future endeavors!