Shenron is a magical dragon and Shenron can bestow any wish as long as it does not exceed the power of hus creator, who must still be alive when he is summoned (i.e Kami or Dende). He is unable to restore life to those that died of old age (but he can restore a person's youth), sickness or any other natural deaths. In episode 8 of Dragon Ball Z Abridged, it is revealed that Shenron cannot grant the same wish more than once, (e.g. bringing back from the dead who have been killed before, etc.) but unlike the original series in TFS he can grant a wish to defeat and or kill an opponent.