Located in the middle of Route 205, the Eterna Forest is similar to Kanto's Viridian Forest. It is a forest enveloped in chilly air. Thick stands of trees turn the forest into a natural maze. The Eterna Forest is home to many Bug- and Grass-type Pokémon and one of the only two places in Sinnoh to catch MurkrowD and MisdreavusP, the other place being Lost Tower.
The Eterna Forest has a reputation for being a mysterious place, from the abandoned Old Chateau to the strange Moss Rock. The Eterna Forest is a long and complex structure of trees that make it a natural maze, of where a lot of people get lost. The Eterna Forest has apparently been the location to numerous sighting of Team Galactic, for many unknown reasons. The Eterna Forest is home to many Bug- and Grass-type Pokémon, and is the only known place in the Sinnoh region to find and catch Buneary. The forest can be broken into three sections - the south western corner; the south eastern corner; and the north eastern corner.
There are several paths that can be taken to get to each entrance, however the most direct route from southern part of forest to the northern part of the forest can be taken by traveling east from the entry, through the tall grass, directly north to a small gap in the tree that travels east to the south eastern segment. If, however, the western road is taken, the route would lead to an Antidote, and the Moss Rock further north.
The next section of the forest is large than the first, as by traveling south, through the large patch of tall grass, the road lead to four sections of trees that are placed in a two by two pattern that allows the path to travel through the tree, in a similar "+" shape. There are several items scattered around the area, as well a few Trainers that are eager for a battle. By traveling north east, the road will soon lead to a large gap, where the road travels north to the north eastern segment.
The third segment turns east where a large square with a dense layer of trees hang in the middle. Simply traveling north through another patch of tall grass will clear the section. To the north is Old Chateau where Cut is need to clear the trees, and to the east is the eastern entry to the forest which has access to eastern Route 205, and Eterna City after that.
A mossy rock is located on the far west side of the forest. It emits a kind of radiation, which extends to cover the entire forest. This causes Eevee to evolve into Leafeon when leveled up within the forest's boundaries except for the Old Chateau. The rock itself is located in the southwestern section of the forest near a formation of trees that resembles a sideways L. Directly to the trees' left is Moss Rock, surrounded by long grass.
Lucas and Gardenia outside the Old Chateau in Platinum
The Old Chateau is located in the north of the Eterna Forest, near the eastern entrance. To gain access to it, the player needs HM01 (Cut), which can only be used after defeating Gardenia in Eterna City. Inside one of its four bedrooms, there is a television, which, if interacted with at night (only after obtaining the National Pokédex in Diamond and Pearl), will initiate a battle with the only obtainable Rotom in the game. In the manga, it is the most scary place in the Eterna Forest according to Gardenia; she also mentions about the shadowy ghosts and figurines residing inside the chateau.
Upon entering, the Old Chateau appears to be old and abandoned. The first room encountered is the foyer, which has two flights of stairs both leading to the first floor. There are also four bedrooms that can be accessed to by traveling further up the first floor. In one of the rooms there is a television that is on and displaying a plain, white, flickering screen. There is also a portrait in another room; glowing red eyes appear on it that will stare at people when their back is turned and will disappear when faced.
What seem to be the ghosts of a little girl and a butler appear in a bedroom on the first floor and in the dining hall, respectively.
Once HM01 (Cut) is able to be used outside of battle, players may take a shortcut around the forest that provides quick access between the northern and southern portions of Route 205. On the path there is a woman who will give the player a Big Tree. There is also a patch of soil suitable for growing Berries and a Honey Tree.
When the player first enters the forest, Cheryl will be waiting, and ask the player if he or she will accompany her through the forest, fearing Team Galactic's possible interference. After this, all battles in the Eterna Forest will be Double Battles, including encounters with wild Pokémon. Her company is very useful - after every battle, Cheryl will completely heal the player's party. However, during battles with wild Pokémon a little problem appears: the player can throw a Poké Ball only when there is one Pokémon left, and thus Chansey's Egg Bomb may accidentally knock out the Pokémon the player wants to catch. In Pokémon Platinum, she gives the player a Soothe Bell as a parting gift.
In The Grass-Type Is Always Greener!, Ash and the group help Cheryl search for the Amber Castle deep in the Eterna Forest, and meet Gardenia, who challenges Ash to a battle. Gardenia wins, and decides to help the group search for a spot where she knows where Combee gather to form a Combee Wall.
In An Angry Combeenation!, the group spot their first Combee Walls, and eventually make their way to the Amber Castle with Mothim's keen sense of smell. After defeating Team Rocket who were attempting to steal the Enchanted Honey, Cheryl receives a gift of Enchanted Honey for helping Vespiquen and the Combee.
The Eterna Forest appeared in The Old Chateau. In the episode, Cheryl and her Chansey were journeying through the forest until they came across the Old Chateau where they went to spend the night.
In forests and caves, there are many
items on the ground that cannot be
seen in the murky darkness.
Take the time to search carefully!
Eterna Forest is known in Diamond and Pearl as "the place where time stands still". As such, it is impossible to evolve Eevee into either of its time-based evolutions, Espeon and Umbreon. Similarly to Route 217, Eevee will only evolve into Leafeon here, due to the presence of the Moss Rock.
However, the light does change during the day (from morning to day, day to evening, evening to night, night to morning).
A Bug Catcher in front of the Eterna Forest will say there are lots of Poison-type Pokémon found there. However, only five Poison-type Pokémon can be encountered there, two of which can only be obtained by dual-slot mode (Weedle and Kakuna) and another two which do not learn any Poison-type moves via leveling up (Gastly and Budew). However, Budew can have the ability Poison Point.
Additionally, all Poison-type Pokémon found here are dual-types with Poison as their secondary type.