To switch from WarioWare to Classic Wario, export the MDL0 of the WarioWare costume and in the Classic costume, replace the MDL0 with the one you exported.
For Classic Wario to WarioWare, do the same thing, but the other way around, and then, in addition to that, you have to add a bunch of bones(Look at the original WarioWare bones to see where these bones go).(JacketSkirtN and its childs, LSleeveBN, LSleeveCN, LSleeveFN, RSleeveBN, RSleeveCN, RSleeveFN, LNeckBandNa, LNeckBandNb, RNeckBandNa, and RNeckBandNb)
Cool. Thanks!