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.
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 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.
When you dress up as a Rocket to get to the radio tower and are told you have to get the key from the director, just head to floor B1 in the Goldenrod department store instead of taking the card key and battling the grunts. Head to the stairs to find the director, then battle the grunt and you're done.
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.
Completing one of the following tasks adds a single star to your Trainer card, so to have 5 stars you must complete all 5 tasks. Note: Shiny Leaves are obtained by speaking with your Pokemon in certain areas on rare Nature-dependent locations.
Defeat the Elite Four and Champion.
Give Ethan or Lyra five Shiny Leaves.
Break records in ten Pokeathlon events.
Win 100 battles in a row at the Battle Tower.
Complete the National Pokedex (except for Mew, Celebi, Jirachi, Deoxys, Phione, Manaphy, Darkrai, Shaymin, and Arceus).
The color of your Trainer Card will change each time you complete one of the following feats. The order of colors is as follows (challenges can be completed in any order): Blue, Bronze, Silver, Gold, Black.
Deafeat the Elite Four
Obtain all Entralink Powers
Obtain all Pokemon Musical Items
Complete the National Pokedex
Get a 49 Streak in both Super Single and Super Double Subway lines in the Battle Subway (Good Luck)
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.
To successfully execute this glitch, you must first perform the Pomeg Berry Glitch, which involves using a Pomeg Berry on a Pokemon with 1 or 2 HP so that its HP loops to 65,535 (displayed as ?35 in-game). Do the glitch, but instead with only one Pokemon and an Egg in the party, making sure the Egg in the top-leftmost slot of the party in the Pokemon menu. Once done, you can then enter battles and use the Pokemon Egg as if it were a normal Pokemon.
It will function as a normal Pokemon: you can view the stats it will have upon hatching, it can level-up by defeating Pokemon, it can learn new moves, and can even evolve. You can also alter the Pokemon inside the Egg in otherwise-illegitimate ways. For example, Pikachu cannot normally know Thunder when hatching from an Egg at Level 5. However, with this glitch Pikachu can. Similarly, you can hatch Eggs with fully-evolved Pokemon.
First make sure you have a Pomeg Berry and a Pokemon who has not had their HP lowered as much as possible already through Pomeg Berries. (If the latter is the case, the use of HP Ups on the Pokemon will be enough.) Get the Pokemon to a very low level of HP (1 or 2 HP). Once done, in the field, use the Pomeg Berry on the Pokemon. This will in turn cause the data in their HP to cycle back to the top of the counter, giving the affected Pokemon 65,535 HP--almost 90 times the possible maximum in the game.
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.
Use the points from the Pokeathalon in the shop to buy certain items. The items change from day to day so, if you want elemental stones and rare candies in the shop, change the day of the week on your DS device.
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.