Can you mix Warhammer Fantasy armies?
For the sake of completeness: 

Now Warhammer Fantasy is rebranded to Warhammer Age of Sigmar, that allows you to play with "whatever the heck you want" in any game. But even if you want to play rules hardcorelly, now they are only 4 factions, Order, Chaos, Destruction and Death. 

All the armies you named in your question are part of "Order" so, by the new rules, they are completely allowed to be used together.