Well first off Ni-mh will not give enough current. Secondly its difficult to know how much capacity you will need.

Are you running the Ev warriors at 24v or at 12. Is the linear actuator motor big or small. How close will the robot be to stall when just running around.

From a rough guess you are going to need atleast 3amp of Ni-cds just to supply the current.

Regards
Ian