How do you evolve Shelmet and Karrablast? Since you can only trade 1 Pokemon at a time, how do you trade Karrablast with Shelmet? Do you trade Karrablast for Shelmet?
Yes, you trade Karrablast for Shelmet in order to evolve the two.
http://pokemondb.net/evolution/trade
You evolve Karrablast by trading Shelmet with Karrablast.They both evolve at the same time after the trade.The same with Shelmet, you have to trade Karrablast. (Hope This Helps!) :)