Stadium/Metal Cup/3

Reward:  2 and 17000

Strategy: For Mercury, use Petroleum/Dark Fire/Pirate at least Lv. 10 with 1 silver star. For Armadillo, use Lv. 10 Cool Fire with 1 gold star and for Jade, use Volcano Lv. 10 with 3 bronze stars.

If you have Pures, use Lv. 10 Pure Flame's Nuclear Hit do defeat Mercury in 1-2 turns. For Armadillo, use Lv. 10 Pure Ice/Pure Metal's Icy Wind/Rust and for Jade, use Lv. 10 Pure Terra with Tumble Weed.

Make sure your dragons are ranked up with stars.