Let's go through them one by one: * A large number of skeletons can be countered with the Cavern Ogre's Killing Blow, but there aren't as many skeletons in the newer versions anymore. * Healing Nymphs can be countered by quickly killing Ents or Nymphs; the Wasp Swarm is weak, but removing the enchantment doesn't always work. * Draining mana from Imps can be countered by any strong, high-initiative unit (it's better for a Warlock to lose one unit than all of their mana, because they won't be able to restore it in battle). * Repairing Gremlins is pointless because it only happens once. * Stalker's invisibility is not protected against area-of-effect attacks (Meteor Shower, Fireball, etc.), and the poison loses its effectiveness towards the end of the battle. * Gnomes, with their high defense, are very weak in attack, so they don't make much of a difference. * However, the specializations of Goblins and Peasants (which can be left unupgraded and kept in the castle with Ellaine) cannot be countered. You can't call them the best, but I think they are much more useful... the rest don't matter.