I personally don't see a point in charge cards in a hunter deck, you should have rhino for that.
But hey, aggro hunter decks are popular with charge... while having no beasts except for owl, buzzard and timber to abuse UTH which is a build usability of which completely escapes me, but hey.
Mage is ok with Enrage and Taunt cards to control the game until they can direct damage the opponent.
Spell is also great, but the thing is there isn't much past Thalnos and Azure Drake with spell damage that is also very good.
Kobold/Thalnos early game can be good for 2 damage arcane explosions tho.
That being said I have a mage deck with only spellpower cards and spells for that stupid do 40 spells daily quest, surprisingly I win quite often.. with 2x 10 dmg fireball in the opponents face. But it is certainly not a very viable build although if you add extra minions something like Mana wyrm, kobold, dalaran mage, ogre mage, azure drake and a water elemental with the rest of being spells I can see that working very well actually.
Warlock Murloc is obviously very popular but IMO Shaman synergizes with them even better because of rockbitter, windfury, flametongue and bloodlust. That and Shaman has hands down one of the best card draw cards in the game which is the
Mana Tide Totem. Actually now that Pagle was nerfed and became very unreliable I'd say
it is the best card draw card in the game and ancestral spirit is also great in keeping key murlocs in the game.
Secondly because of Bloodlust shaman also synergizes ok with token builds.
Paladin probably synergizes the best with Divine Shields and Blood Knight, while Priest synergizes well with healing cards and high HP cards to abuse Inner Fire with.
Druid synergizes the best with tokens as in cards that summon other minions either as a battlecry or effects, because of the mass buffs like Power of the Wild and Savage Roar or the super super obnoxious Soul of the Forest and Cenarius.
That's why you want token cards in your deck, things like Violet Teacher, Imp Master and ironically Illidan are good to flood board with then buff with Cenarius or your buffs and ??? profit.