With a well aimed Item Slide, it is possible to grab the edge of the two pillars with switches on them. Doing this and then using the Command Melody to fly Medli up to the second switch is faster then walking over and flying with Medli to the left switch.
Note that this trick requires at least 3/4 of a full magic meter to perform. After flying to the first switch in the first room. Place Medli on it and then jump off to the right and do three to four Leaf Pumps to make it as Link to the other switch. After pressing it down, do three to four leaf pumps back to the first switch to grab Medli.
Throw Medli into the center of the ray of light and kill all of the red and green chus. Go back to Medli and walk around her in circles until all of the purple chus have turned to stone. Then kill them with Skull Hammer jumpslashes.
After the cutscene which shows off the giant statue in the front plays, do a sidehop to the right and move to the right some more while still holding ZL to target, run off the ledge when you're almost near the wall and then once Link is above the skull peg, press A to drop Medli and spam the button which you have the Skull Hammer on.
In the room with the two switches and the staircase, pickup Medli and head over up onto the second platform on the right. Angle yourself towards the ledge. Jump off and fly about halfway with Medli, then drop her and glide the rest of the way to the DARKER ledge with the deku leaf and grab it. From here, use the Command Melody and fly Medli up to you.
Place Medli on the back switch, then jump onto the front switch to lower the staircase. Immediately after the cutscene, sidehop to the right continuously, until you land on the first step of the raising stairs. From here, use the Command Melody to fly Medli over to you.
Similarly to Method 1, pickup Medli and head over to the same ledge on the right and angle yourself with the top of the staircase ledge. Throw Medli, and if you aligned yourself properly, she should land on top of the staircase. Now angle yourself towards the staircase again and pull out a bomb. As the flashing speed increases, jump off of the ledge and pull out the deku leaf to Damage Boost to the ledge. Unlike Methods 1 and 2 you don't need to use the Command Melody in this method.
In the room with the blocks and the floor master, push the first block into the indention on the floor to open the skylight. Pickup Medli and align facing the breakable wall, between it and the spot of light. Now place Medli and 'call' her. Walk away from the wall and the light will reflect off Medli's harp and reveal the block.
Backup towards the ledge, so that your back is facing the sarcophagus. Backflip towards the sarcophagus, and pull out the deku leaf to glide back to the higher platform. This should have disturbed the sarcophagus and revealed the key. Simply use the boomerang to bring the key to you.
Jump off the ledge and glide to the top of the coffin with the key. You will want to make sure to glide at it from a far enough distance away so that the coffin begins to rattle before you land on top (otherwise it will knock you off). Now glide back to the ledge and boomerang the key.
Jump attack on top of one of the stalfos' coffins (either one will work), then jump off at an angle towards the center of the room and use two Leaf Pumps while turning to the left or right (depending on which direction the ledge is) to grab the ledge leading to the Mirror Shield. Note that you can only grab the DARKER part of the ledge, not the lighter part.
On the upper ledge in the statue room, pick up Medli and maneuver over to the edge of the ledge nearest the giant statue. Now turn around, go into first person and lean downwards and slightly right. While still holding that angle in first person, backwalk off the ledge behind you. If you did it correctly, Medli will land on the ledge and Link will hang from the ledge. If Medli falls, you weren't looking downward far enough, if she's not on the edge of the ledge, you were leaning too far downward. If Medli is in the proper position, tap right to perform a Ledge Clip using Medli and then climb up OoB. From here pick up Medli, angle yourself slightly more to the right in first person mode and do a sidehop down to get behind the statue.
To perform this, you must do a bomb roll clip on either ledge beside the stone and simply fly with the leaf out of bounds and behind the stone.
It is possible to skip the small key in the second half of Earth Temple. To do this, first you must place Medli next to the grate that separates the two rooms with the Giant mirror and the last big elephant statue. Now shoot the rightmost red flag that blocks a small alcove with a joy pendant in it. Use the Leaf to fly to this alcove and grab the right most edge, from here do a Roll Clip to the right and use the leaf again to fly back in bounds in between the collision of the grate. Now pick up Medli and take her through to the other side of the room with you.
Alternatively you can also use a Bomb Roll Clip on the right or left side of the ledge in front of the grate to get OoB and skip the small key.
With a few well angled Item Slides it's possible to get on top of the giant mirror in this room as Link and use the Mirror Shield to break the elephant on the other side of the room.
If you have Medli with you, you can play the Command Melody to make her fly and go on top of the mirror. From there, she can also break the elephant statue. This is useful if you got the light arrows early to defeat Jalhalla, and don't have a mirror shield.
In the room before the coffin room where you have to play the Earth God's Lyric, angle yourself so that you're facing the statue and backup a bit so that if you throw Medli she'll land in the light from the giant mirror behind you. Throw Medli and she should land in the light at the proper angle so that the light will reflect off her harp. Now quickly pull out your sword use the mirror shield to bounce the light onto the statue.
By opening the chest in the coffin hallway room, you can Item Slide from on top of the chest to the top of a coffin on the opposite side of the room. From here you can fly over to the coffin to the right of the opened chest and perform a Ledge Clip to get out of bounds and fly with the leaf in between the door and the song stone.
By standing on top of the first mirror in this room with either Link or Medli, it's possible to light both eyes without moving around the mirrors on the left half of the room.
Stand in front of the statue and the stairs preventing the access to the boss key room. Look on the side, perform a backflip and pull out the leaf to glide towards the ledge. Perform a frame perfect roll clip to go out of bounds. From there, you can leaf to get behind the door and open it. Be careful, as the stairs will try to push you back in bounds.
Once you enter the mirror room, head over to the right ledge. Using either Medli or a bomb, ledge clip OoB. Just as you clip OoB, hold L and turn Link so that he is facing away from the ledge he used to clip. Now use leaf pumping to get underneath the ground by the far door. If you continue holding L while leaf pumping, you'll have a much easier camera angle to deal with. Once you get back in bounds by the door, side walk, keeping close to the wall in front of you (you want to be careful not to clip too far into the barriers behind you. Now open the door and proceed.
By performing a bomb roll clip on the ledge near the last warp pot, you can use the leaf and 8 leaf pumps to glide out of bounds around behind the boss door. If you attempt this trick and fall down after doing the partial Ledge Clip portion, this means that your ledge clip inputs were too early. However, you can recover from this quickly by letting one of the floormasters at the bottom of the room take you back to the beginning of the dungeon. From here you can backtrack one room and go through the warp pot right back to where the boss key skip is performed.