They are both in Route 7 in grass. Sword has a higher chance for Karrablast and Shield for Shelmet, but they need to be traded in pairs to evolve. Like if I give you my Shelmet you need to trade your Karrablast so they can evolve and viceversa.
Cool, now you need to get a Shelmet and i'll trade in my Karrablast. If you have a Ditto the easist way to get a Shelmet now is to breed the Accelgor you now have with a Ditto.
Lunatone for a Solrock
Croagunk for a Scraggy
Vullaby for a Rufflet
Sableye for a Mawile
Ponyta for a Farfetch'd w/ Leek
Oranguru for a Passimian
Eiscue for a Stonjourner
Corsola for a Darumaka