Right after you enter frost cavern, go to the right of the first cave, then after you go up the stairs, turn right. Slide across the ice, then climb the stairs. Then solve the ice puzzle. When you are almost done with the puzzle, hit the big rock next to the hiker. turn left, keep going, then up by sliding across the ice. After you find the karate guy go straight down from him. Fight the battle girl, then go left until you see the big ice shard. Go down, solve the puzzle,then take the stairs down, then go up the stairs by the hiker. The ace trainer will heal your Pokemon there. Go up the next staircase, then keep going straight forward. There's team flare. Hope I helped!
Source: did this a few seconds ago