You can't class a breed, it has to be measured based on finish and trim. The lean portion of all beef will be the same in calories, the amount of fat will vary, but the fat will all contain similar calories.
Wagyus have been bred to marble, some studies show they marble only at a later age and are slower growing. A well marbled Wagyu that grades choice will have the same fat content as any other breed that grades choice.
The choice grade starts at 4% IMF (intramuscular fat). This has no bearing on external fat, but that fat is usually trimmed to 1/8" so is constant on all beef cuts.
For actual caloric and fat content of beef, visit <A HREF="http://www.beefinfo.org" TARGET="_blank">www.beefinfo.org</A> (I think). Others will post if that URL is wrong.
Jason Trowbridge Southern Angus Farms Alberta Canada