In the same rooms where you have to complete a picture puzzle of Omanyte, Kabuto, Aerodactyl, or Ho-Oh, there is a plaque that has a word that is spelled using Unowns. Do the following steps.
Room with the Kabuto Puzzle The word is "Escape". You must use an Escape Rope facing the plaque. You can easily get an Escape Rope at the Violet City Pokemart. The four items obtained are Energy Powder, Heal Powder, Oran Berry, and Pecha Berry.
Room with the Aerodactyl Puzzle (accessible by Surfing) The word is "Light". Use Flash while facing the plaque. The four items obtained are Energy Root, Heal Powder, Moon Stone, and Sitrus Berry.
Room with the Ho-Oh Puzzle The word is "Ho-Oh". You must have Ho-Oh first in your roster. The items obtained are: Charcoal, Leppa Berry, Life Orb, and Revival Herb. In Pokemon HeartGold, Ho-Oh is obtained in the Bell Tower. In Pokemon SoulSilver, Ho-Oh is obtained after you have defeated the Elite Four. Room with the Omanyte Puzzle The word is "Water". You must have a Water Stone in your bag. The items obtained are: Leppa Berry, Mystic Water, Stardust, and Star Piece. A Water Stone can be obtained by winning it at the Pokeathlon on Wednesday.
At Celadon City, enter the Celadon Condominiums next to the Pokemon Center. Use the elevator to reach the third floor. When you exit, your friend will tell you about the GB Sounds. Talk to the man next to the globe after collecting all of the Kanto badges to get the GB Sounds Device. If you turn on the GB Sounds option before entering the Union room, then trade with someone, it will play the classic trade music.
To unlock secret box wallpapers and Pokemon eggs, go to Violet City Pokemon Center. Tell the man next to the PC certain words when he asks you for your opinion. Use this website to generate these words.
Unlock the following maps by performing the corresponding tasks:
MAP - HOW TO UNLOCK Beautiful Beach - Get 200 Watts. Beyond the Sea - Get a foreign Pokemon by using the GTS. Big Forest - Get 40,000 Watts and own the National Dex. Blue Lake - Get 2,000 Watts. Dim Cave - Get 1,000 Watts. Hoenn Field - Get 5,000 Watts and own the National Dex. Icy Mountain Rd. - Get 30,000 Watts and own the National Dex. Night Sky's Edge - Trade a fateful-encounter Jirachi onto Pokemon HeartGold or SoulSilver. Noisy Forest - Available by default. Quiet Cave - Get 100,000 Watts and own the National Dex. Rally - Participated in the Wi-Fi Event during January 29th through February 28th, 2010 in Japan. Refreshing Field - Available by default. Resort - Get 80,000 Watts and own the National Dex. Rugged Road - Get 50 Watts. Scary Cave - Get 20,000 Watts and own the National Dex. Sightseeing - Participated in the Wi-Fi Event during November 14th, 2009 through to January 11th, 2010 in Japan' and from April 17th to May 31st, 2010 in Korea. Sinnoh Field - Get 25,000 Watts and own the National Dex. Stormy Beach - Get 65,000 Watts and own the National Dex. Suburban Area - Get 500 Watts. Town Outskirts - Get 3,000 Watts. Tree House - Get 15,000 Watts and own the National Dex. Volcano Path - Get 10,000 Watts and own the National Dex. Warm Beach - Get 7,500 Watts and own the National Dex. White Lake - Get 50,000 Watts and own the National Dex. Winner's Path - Participated in the Wi-Fi Event from May 6th to June 25th, 2010. Yellow Forest - Participlated in the Wi-Fi Event from April 1st to May 5th, 2010.
To get Oran Berries, Go to the betting corner at the sixth floor of the Goldenrod Department Store and pay 300 to draw a ticket that wins you a #1, #2, or #3 prize. The #1 prize is the TM of the day (the woman next to the ticket counter tells you what prize #1 and #2 are). The #2 prize is a special Pokeball, while the #3 prize is a random selection of one of ten different berries, including the Oran. Do not waste your money by trying to get a lot of them.
You must give the Miltank seven Oran Berries. The best way is to harvest the berries in the berry pots until you have seven of them. Alternatively, the girl to the left of the Miltank will give you a seal case and the girl on its right will give you three seals. The farmer woman also gives you a TM Natural Gift. Once you give the Miltank all the berries, you can buy Moomoo Milk (which heals 100 health) for 500. In Olivine, the girl in the house north of the Pokemart will give seals.
Watch the Clefairy dance on Mt. Moon on Monday night between 8:00 p.m. and 12:00 a.m., then wait for morning without leaving the area. When daylight comes, the full moon's reflection will still be in the pond. An easy way is to save the event, save the game, close the DS, and waiting until morning.
In Ecruteak City at the Dance studio, a Team Rocket grunt is hassling a kimono girl. Talk to the person on the right side of the stage. He tells you he would have put a stop the grunt's behavior if it was not for the incredible pain of his stomach ache. This is a tactic commonly used by Hercule Satan in Dragon Ball Z to get out of fighting.
Go to Ecruteak City and challenge all the Kimono Girls (one after another, no rest). You'll get the Crystal Bell and you can proceed to capture Lugia. Make sure you already defeating all 8 gym leaders and have the silver feather btw.