For the measurement of pullulanase I would recommend using the Pullulanase (K-PullG6) assay kit: Pullulanase/Limit-Dextrinase (PullG6 Method) (K-PullG6) Data Booklet
If you wish to use a polysaccharide then we suggest the borohydride reduced version as this will generate a lower background in a reducing sugar assay when measuring hydrolysis by pullullanase.