This thread details the locations of emotes in Sky! It's not all strictly spoilers since some are *very* obvious, but consider the entire thread a spoiler if you haven't played or haven't collected all emotes at least once!
Prairie Wave On the small island near player spawn point.
Butterfly Two players required to open the gate, but there's another way in. Through the two-person gate near the wave emote, or down through one of the holes in the roof.
Yawn Light the candles at the shrine at the base of the broken tower, collect the emote at the top.
Medium-Wide Stance 4 Players Required On the Island with boat docks, behind the 4-player door.
Brow-mop / Sweating 2 Players Required From the Island with boat docks, ride the 2-player boat. It will take you across the clouds, open a door, and dock next to the emote shrine.
Bird Voice Head toward the high island with the stupa on top, but stay low. Pass over a bank of clouds and you will see a secluded small island with 4 candles and a stone arch. Light the candles to gain the bird voice.
Prairie - 8 Player Gate Clapping Requires 2 players. Enter the 2-player gate on the far island.
Candle Up Requires 8 players. Enter the 2-player gate on the far island. Then get 8 players to simultaneously activate the lock mechanism. Once the lock opens and the platform lifts you, light all the candles surrounding the platform.
Forest - Part 2 Worship / Deep Bow 2 players recommended, but not strictly required. Left of the path, after the first hill but before the tree tunnels. Burn all the Corruption and the branching plant behind to access the shrine. The plant is very difficult for one player to remove without help.
Manta Voice 2 players recommended, but not strictly required. Burn the Corruption that has entangled 3 mantas. The plants can be very difficult for one player to remove without help.
Whale Voice Burn all the Corruption that has encased a large skeleton.
Facepalm 2 players recommended, but not strictly required. Right of the main path, under/beyond a large fallen tree. Burn the branching Corruption plant to access the shrine. The plant is very difficult for one player to remove without help.
Cry / Weep / Tantrum Two entrances in a hill are blocked by Corruption. Burn the Corruption to access a cave. Light all the candles in the cave to gain the emote.
Forest - Part 3 Thinking / Bright Idea 2 players required. A doorway on the right is blocked with Corruption. Burn it to enter, open the lock, then 2 players must activate the mechanism to gain the emote.
Valley - Part 2 Bow Back-flip Wide/Proud Stance These 3 emotes are collected in the form of orange sparkling butterflies during the race. The first is in a gazebo and is hard to see. The second is on a bridge that is best approached from above and flying directly at it, not by jumping off the ground when you're near it. The third is in the final stretch and should be hard to miss!
Vault Pray Requires 4 players. Requires "Telekinesis" emote. Turn right after the entry hallway and there's a wall with 4 stones next to it. Lift all 4 stones into place using the Telekinesis emote.
Telekinesis Requires 4 players. On the second level of the vault, there's a large door with 4 handles. Open that and the shrine is inside on the right.
Shy / Narrow Stance Requires 2 players. Requires "Blow a Kiss" emote. On the third level of the vault there are floating islands in the dark. Two have candles that will grow small trees, and those lead the way up to the shrine.
Levitate Requires "Pray" emote. On the fourth level of the vault there are floating islands. One has a hole in it and a shrine surrounded by candles. Many players can pray, but only one is required.
Spirit Manta Voice Requires "Manta Voice". On the third fourth level of the vault there are floating islands. The highest has a small cluster of bones. Light the candles and a ghost manta will appear to give you the voice.