In the General Rules for Regular Category the following is stated:
Materials used to assemble robots, including controller, must be from LEGO MINDSTORMS sets. This means that all LEGO MINDSTORMS article numbers are accepted. Further, teams are allowed to use elements from several LEGO MINDSTORMS sets. WRO recommends use of Education versions of LEGO MINDSTORMS due to extended service available from LEGO Education distributors.