From StrategyWiki, the free strategy guide and walkthrough wiki

The Gym has boulders like in the Ice Cave, when you go up to Level 2, there are two boulders, you can only push 1 of them into the hole though, to do thispush the one on the right up two, then push the left one into the hole, it doesn't do anything so go south and battle the Cooltrainer♀. When you get past her, push the far right block down all the way, then move the other one up 9 places then to the right, now for the final Boulder, battle the Cooltrainer then push the rock all the way to the right then push the other one down.

When you beat Claire, she says you have to go to Dragon's Den for a test before you get the final badge.

[edit] Trainers

• Cooltrainer Paul: Dratini Level 34, 480 EXP, Dratini Level 34, 488 EXP, Dratini Level 34, 488 EXP, 1632
• Cooltrainer♀: Fran: Seadra Level 37, 1220 EXP, 1776
• Cooltrainer Cody: Horsea Level 34, 594 EXP, Seadra Level 36, 1188 EXP, 1728
• Cooltrainer Mike: Dragonair Level 37, 1140 EXP, 1776
• Cooltrainer♀ Lola: Dratini Level 34, 480 EXP, Dragonair Level 36, 1110 EXP, 1728

[edit] Leader

• Leader Claire: Dragonair Level 37, 1141 EXP, Dragonair Level 37, 1141 EXP, Dragonair Level 37, 1141 EXP, Kingdra Level 40, 1773 EXP, 4000 (She tells you to go to Dragon's Den)