0x0 - Healing - who could forget that?
0x1 - 2 Returns 0, but has something to do with var 0x7EA1…no idea.
0x2 - Blacks out the screen.
0x3 - Blacks out the screen, returns you to the last warp you used on current map. If you didn't use a warp on the map you were on, then returns you to center of the map you were on.
0x4-0x7 - Returns 0x933F (37695), but does nothing visible.
0x22 - Trading menu.
0x27 - Returns 0x933F (37695), but does nothing visible.
0x28 - Saves party Pokémon into RAM.
0x29 - Reverses changes from 0x28.
0x2A - Chooses 3 Pokémon, relocates those three to 0x203CEF8.
0x2C - Returns to 0x8004 - the status of the Loamy Soil of 0x800F, 0x8005 - the "beauty" of the Loamy Soil plant, if there is one. When it is 0xFF, all scripts are programmed to return a msgbox "!", possibly displaying a state change. It will return 0x0 through 0x5 depending on the state of the Loamy Soil, from 0x0 being not planted at all, to 0x5 being fully grown.
0x2D - Something to do with the Wailmer Pail.
0x2E - Stores into memory the type of Berry you chose to plant and how many Berries there are ("beauty"?), and returns into \v\h03 ([buffer2]) how many Berries there are, if any, and \v\h02 ([buffer1]) what type of Berry plant it is.
0x2F - Allows you to choose a Berry from the Berry pocket of your Bag. Affects 0x800E.
0x30 - Something to do with planting berries.
0x31 - Probably returns into 0x8004 how much room that you have left in your Berry pocket. If none, then 0x0 is returned.
0x32 - Something to do with picking Berries.
0x33 - Does something about the "beauty" of the plant.
0x34 - 2 Appears to return 0x1 into specified variable if Player has a Berry available.
0x3B - Starts playing the "Trainer Spotted!" music depending on the trainer class indicated by 0x8015.
0x3C - 2 Checks if Rematch available. Returns 0x1 as yes.
0x3E - Makes a trainer battle happen. Turns Player to left after done.
0x3F - Displays a second text box displaying all the possible options for the POKéMON Storage System. Ends and returns to script if you select "SEE YA!".
0x61 - Plays the actual "watering" animation, and possibly even sets the effects of the Wailmer Pail…
0x62 - "Trendy Phrase". Used by the Trendy Dude outside in Dewford Town.
0x86 - Checks how many Pokémon in Party and places in Variable. Identical to FireRed 0x83. (Credit to JPAN and buddies)
0x87 - I assume this is identical to 0x86…
0x8E – Used first in the Mauville City Gym switches.
0x8F – Used second in the Mauville City Gym switches.
0x91 - Map refresh. Identical to FireRed 0x8E.
0x9D - Better set the clock!
0x9E - Now look at the clock.
0x9F - Starter Pokémon; Birch's Bag
0xA0 – Wally Meets Ralts! - Wally sends out first Party Pokémon unless special paramaters are set.
0xA1 - Nickname Pokémon in Party, as indicated by 0x8004.
0xA2 – Choose a Pokémon. – Sends it somewhere.
0xA4 – Berry blender.
0xA5 – 2/ Roulette game. Somehow returns 1, then 3. Has something to do with 0x8004 and cmd96.
0xA9 - Returns 0x933F (37695), but does nothing visible.
0xAE - Generates a wild battle from the "Tree (Rock Smash)" wild Pokémon data. May have a chance of returning 0x0 into LASTRESULT; 0x0 means no battle.
0xB7 - 2 Checks how the last wild battle ended. 0x1 if won, 0x4 if lost, 0x5 because it can, 0x7 if captured.
0xB8 - Buffers the two Day-Care Pokémon into \v\h02 ([buffer1]) and \v\h03 ([buffer2]). Identical to FireRed 0xB5. (Credit to JPAN and buddies)
0xB9 - 2 Returns 0x1 if there is an egg, 0x2 if one Pokémon, 0x3 if two Pokémon. Identical to FireRed 0xB6. (Credit to JPAN and buddies)
0xBA - Clears Egg timer, prepares it for new timer. Identical to FireRed 0xB7. (Credit to JPAN and buddies)
0xBB - Creates and places egg in Party. Identical to FireRed 0xB8. (Credit to JPAN and buddies)
0xD9 - Turns the tile above the player that is also directly bordering the script tile into the 6th tile in the tileset, and flickers it between the 5th and the 6th tile for a while. Used for PCs.
0xDA - Turns the tile changed in 0xD9 into the 5th tile in the tileset. Used for PCs. Changes the movement to "blocked"?
0xF4 - Stops all music.
0xFC - Player's PC.
0xFD - Player's POKéMON Center PC. Returns to script when "TURN OFF" is selected.
0xFE - HOENN map.
0x109 - Sets up a second text box displaying all accessible PCs, displaying "LANETTE's" instead of "SOMEONE's" if you have seen her. Returns to 0x800D (LASTRESULT) 0x0 if you chose Pokémon Storage; 0x1 if you chose "\v\h01's PC"; 0x3 if you backed out by selecting "LOG OFF"; 0x7F if you backed out with the B button.
0x129 - Used in a manner like FireRed 0x127. Something to do with [0x3005DF0].
0x12A - Used in a manner like FireRed 0x128. Something to do with [0x3005DF0].
0x136 - 2 Seems like it checks for Pokérus in party; returns 0x1 if indeed Pokérus exists.
0x137 - Returns 0x933F (37695), but does nothing visible.
0x138 - Takes variables from 0x8004 (dyp), 0x8005 (dxp), 0x8006 (length, in shakes), and 0x8007 (frames between shakes?) and makes an earthquake.
0x13A - dowildbattle for RAYQUAZA.
0x13B - dowildbattle for the Regis.
0x13C - Returns 0x933F (37695), but does nothing visible.
0x13D - Jostles the screen up then down in medium speed.
0x13F - "Flash grenade" effect.
0x140 - Same as 0x3.
0x141 - Same as 0x140, but with a fall-animation instead.
0x143-0x144 - Returns 0x933F (37695), but does nothing visible.
0x145 - Normal battle.
0x146-0x148 - Returns 0x933F (37695), but does nothing visible.
0x14A - Returns 0x933F (37695), but does nothing visible.
0x15E - Something to do with planting Berries.
0x15F - Something to do with picking Berries.
0x19F - Checks for Wireless. 0x1 true, 0x0 false. Identical to FireRed 0x16A. (Credit to JPAN and buddies)
0x1A5 - 2 Checks if someone is linked to you, and puts their name in \v\h02 ([buffer1]), otherwise clears buffer. Identical to FireRed 0x183. (Credit to JPAN and buddies)
0x1A9 - 2 Checks for bad Union Room Pokémon, then returns 0x1 if indeed there is. Identical to Fire Red 0x1AE. (Credit to JPAN and his buddies)
0x1D9 - 2 Checks for Trainer Stars; returns to given variable how many stars. Notably used by Nurse Joy for "special treatment"
0x1E6 - Names a Pokémon that is to be sent to the PC.
0x1E7 - 2 Returns to given variable the current default box name. Moves default box forward one?
0x1E8 - 2 Returns to given variable if the box is full. 0x1 means full.
0x1E9 - Takes value in 0x8004 and registers in the POKéNAV the corresponding Trainer.
0x1F3 - Obtain National Dex!
0x203 - 2 Checks if [Map Block] +8 bytes is equal to 0xA02. Probably vaguely has something to do with Linking. Identical to FireRed 0x1B1. (Credit to JPAN and his buddies)