By talking to May at the entrance to Ice Cave after catching all her Pokemon, the party can engage in battle with them in a short boss rush. The following battles must be won without changing your party or refilling your inventory (although the party is fully healed between fights):
In addition to the Pokemon having more health and some having more damage and moves, every three turns May will heal a random active Pokemon for 30,000 HP.
The prize for winning is 100 Galaxy Coins and Soul Dew. If the party already has Soul Dew, the prize is just 100 Galaxy Coins.