Yes, the small-batch size at IIM Shillong or that at any new IIM provides a considerable advantage during placements. The older IIMs have a larger batch size therefore the competition is also tough. So an average profile will get an average CTC only. Whereas at IIM Shillong, the small batch size means lesser competition and better placement opportunities. With less talented people around, someone with even an average profile can get a high package.

The small batch size can be beneficial only if you have a decent profile. A below-average profile can not get you a good package even at a college with a smaller batch size like IIM Shill