Pokemon Found in Deep Snow
Head over and talk with the people. When you're ready to, hop onto the Mamoswine. Time to ride it through the deep snow. Follow the path south, then east. When you see the breakable blocks framing the snow, break them by pressing the A button whilst on Mamoswine.
Smash the rocks blocking the paths leading north and east. Now dismount the Pokémon with the B button and take the path leading east. Here you'll find a Sky Trainer here. Feel free to take her on!
Sky Battle: Sky Trainer Anila
Once that's all done, head back to the Mamoswine and take the path leading north this time. When it splits into two paths leading east and west, take the west one. Turn on your Dowsing Machine and follow the path to the very end when it turns north. You'll find a Timer Ball there.
Now head south a little and take the path leading east. At the end you'll find an Icicle Plate. Once you have it, head back to Mamoswine. Hop back on, move back into the deep snow and head south then south-east through the snow. You should see some rocks to your south.
Have your Pokemon break them then move out of the deep snow and have him move down and break the rock blocking the snow ramp up. Dismount and head down the path. When it splits into two paths, take the west one and it'll loop around to an item. Pick it up to find that it's a Calcium . Move back to the Mamoswine and mount it once more.
Tip #048: Pokemon Vitamins
Vitamins like Calcium instantly boost your Pokemon's stats, but there are limitations. What they actually do is increase your Pokemon's EVs by 10, which in turn boosts your stats. However you can't use vitamins to boost a stat if there are 100 EVs or more in that stat. Also you can't use them if your Pokemon has 510 EVs across all stats.
Move back into the deep snow and follow the path east. You'll eventually reach the end with rocks blocking your way. Break them, head on through and dismount. Head east up the ramp. As you're starting to get back into the grass area you'll receive a Holo Clip from you rival. They'll want to battle you in front of the next gym.
Anyway, head on over to the gate. Turn on the Dowsing Machine to find the Paralyze Heal just north of the gate. Now follow the thin path north from the gate and you'll find a Rare Candy just sitting there. Once you have it, head on through the gate!