When first entering the ametrine mountain, the player will meet Aya, Cain, and Hardy next to a huge solid ice wall. After some attempts to break the ice, Hardy suggests that they should go to Calcenon City first.
After obtaining the HM Dive from Charlotte, the player will have access to battle the PULSE Avalugg located in the center of the mountain. After defeating the PULSE Avalugg, the road towards Ametrine City will be accessible.
Later on after successfully rescuing Heather, the player will team up with Cal and Shelly to chase Blake in the mountains. Before reaching the mountain peak, Aster will challenge the player to a battle ONLY IF the player chose to NOT give the ruby ring to Blake. After the player defeats him, he hands the player the HM for Waterfall and resigns from Team Meteor. When the player reaches the peak, Shelly has already lost to Blake and Blake will challenge the player to a double-battle. Shortly after losing to the player, Team Meteor's helicopters arrive and Blake escapes.
After activating TMX Waterfall, head to 1F of Ametrine Mountain using Waterfall. You will see to the right a Sneasel attacking one of the smashable rocks. Interact with the rock its facing and use Rock Smash. It will attack you and you have the opportunity to catch it.
Go from 1F of Ametrine Mountain and use Dive, you will end up in B1F. Navigate your way to the north side up B1F to find another dive area. When you get to the underwater area, go south and you will find a hidden entrance. You be end up in a bigger area underwater. If you come here on Friday (although if it does not, try the weekends), you will find a Lapras swimming around. Interact with it to battle it. If you go to the south west of this area, you will find another hidden entrance which contains an Abomasite.
Make sure you bring some PokeSnax to activate this event. From B1F, go to the south east of the area and use waterfall to go to B2F. Then go to the very left then go up (using waterfall multiple times) to find a Totodile jumping around. Try to interact with it when its above the water to battle it (make sure you have PokeSnax first).
After you get TMX Rock Climb, head to Calcenon City and go to Ametrine Mountain from there.Then use waterfall to go to 3F of the mountain and make your way to another waterfall. Use waterfall again to end up in 4F of the mountain. Surf up to find an area you can land on to find an ice puzzle. Hop down the ledge you see to hit a rock, the go right to hit a wall where you can use Rock Climb. Go up to find a ladder which leads you to 5F. Solve another ice puzzle to find a waterfall to go down from. After a long sequence, you will end up in B4F where you can find an Icium Z. You also have a chance to fish for a Dratini here using a Super Rod.