The playing field is rife with possibilities, only restricted by your imagination.
The lesser dragon somewhat worries me, since a slightly cheaper attacker with a bit less hp/stats than the real dragon could easily flush out the existing midrange attackers we have. Though I highly suggest one of those lesser dragons for elements like light and especially time, for air maybe. (It has the FFQ so mwoah) This can open new ways of play. Why no time rush? I barely see any low level time units. The scarab costs 2 but needs gravity, and it has too low attack alone... Scorpion also needs a buff to be activated, so it's not a real rush card. So when you think of it time barely has 1 midrange attacker!
Now, if the lesser dragons were somewhat expensive, but with a good ability, they would cut into the nymph field again.
So, if you added an ability it would have to be unique. Dragons fly and are thought to be good attackers, so why not emphasize on that? While there is a lot to choose, I just thought of this, working out my idea:
Lesser dragon: Midrange attacker with medium stats, but for slightly increased cost. (5 or 6)
Air does double damage through earth shield. (If no shield then damage is normal)
Earth does double damage through air shield.
Death does double damage through life shield.
Life does double damage through death shield.
Darkness does double damage through light shield.
Light does double damage through drakness shield.
Water does double damage through fire shield.
Fire does double damage through water shield.
Entropy does double damage through gravity shield.
Gravity does double damage through entropy shield.
Aether does double damage through time shield.
Time does double damage through aether shield.
And do not ask me why gravity and entropy or aether and time are opposites, because I don't know. Thanks.