This is the most important point.
>These Pokémon will appear randomly in one of the six areas
This is the full section.
>Some Pokémon will not always appear in the Marsh. Each day, the Pokémon will change, therefore, to get a new set, players must wait a day. These Pokémon will appear randomly in one of the six areas, some may not appear for a while, while others appear several days in a row or in multiple areas on the same day. Some may not appear until after getting the National Pokédex. The only way to tell which changing Pokémon is available in the areas for the day is to use the lookout upstairs from the entrance. Record mixing also changes the changing Pokémon of the day in the Great Marsh so all players mixing records have the same Pokémon on the same day.
In order to find out what Pokémon are going to be in each area daily, the player is able to walk up to the second floor in the lobby, and use the binoculars and look out onto the marsh. For 100 players can get a brief glimpse of the Great Marsh showing certain Pokémon in certain areas of the marsh. In each slide, a part of the park will appear with a Pokémon in the center of the slide that can be found in that area.