It can be sub'd though. The cross and lightning mail are close because they draw power from the same sorce, And virtualy do the same thing.
Cross is the slower version with a wider range, and LM is very fast and a smaller range.
The design of the game could alow thouse 2 to co-op in 1button catagory. However, B-> & SmashB(dash) are catagorized as to diffrent moves, same family. Most charecters dont have this function, but its there. Richter would be equiped with this ability.