Life Buildings

Well, you can level up one hero so that they walk ahead of the champions, right? And what kind of hero it will be (with what spells) depends on the initial idea, and here, whether it's teleport or dispel, it doesn't matter in terms of obtaining it.
So, dispelling before the champions... the problem is that they'll be put in the first row, and they can be hit there or a bad spell can be cast on them.

Are you playing against a Birch Grove, or something? It will be the same – one or two heroes will outrun the champions, so you'll be dispelling them so that they can actually move. :)
Unless you teleport them. In general, fighting with champions, as well as with catapults, gargoyles, and other creatures, is always improvisation. You can only rely on surprise attacks. For example, Dima Stranger brought 300 elves with a direct arrow to PowerSpot and won. :)