Hover over the icons under "Damage" to see list of attacks.
Strategy: This combination worked with Level 18 Dragons: Use a Chameleon Dragon against the Laser. His HP is high while, he takes little damage from Flame and Electric and he has a Level 15 Electric attack untrained. Use a Gold Dragon against the Medieval. He has good HP and it is hard to get a great defense against Flame and Metal, but his defense is at least good. His best attack is a Level 10 Electric untrained, but if you had time to train him before, he could be even more effective. Use a Waterfall Dragon against the Vampire. He takes small damage, has normal HP and has a Level 15 Sea attack untrained. But if you have Legendary Dragon above Level 17 with legend spell they work great!
Alternate: Another strategy to win very easily is use a Gummy Dragon of Level 15. Accompany it with any Level 15 Dragons that have unlocked a Sea attack at its Level 15/trained a Sea attack for a sure and rapid win. Make sure that they have at least 2 silver stars.