Hover over the icons under "Damage" to see list of attacks.
Use Gummy Dragon first with Poison Ivy to lower Waterfall's HP. Use Cool Fire with Snow Storm to defeat Waterfall Dragon. Finally, use Petroleum Dragon with his strongest water attack to defeat both Chameleon and Cactus Dragon.
Or, you can use rare hybrid dragons like Cool Fire Dragon (not for Waterfall Dragon or Chameleon Dragon), Soccer Dragon and Armadillo Dragon (This will be a hard fight if your dragons aren't at least level 20 and ranked up with stars).
|Cool Fire Dragon||30|