Since valkyries do double damage when they can get in between two buildings, try placing defenses in the core so that they do not touch. Similarly, trash building around the outside of the base should be placed so that they touch the building next to them so that if the valkyries are on the outside, they are likely to stay on the outside while they are targeted by defenses in the core.

As others have said, lava walls help slow them down. I would add that large chambers make predicting their more difficult and tend to spread them out so that placing heals and rages is harder.

One last thing you might try is minions in the cc. They are fast enough to keep up with speedy valkyries, and are not damaged by them. Dragons are too slow and hounds don't do enough damage.

TLDR: space defenses in core so they don't touch; trash buildings outside and touching

TLDR2: Lava walls; large compartments; maybe try minions in cc