Hopefully, this may help:
"Dream Pals
A player can become Dream Pals with another player by visiting their house and sending a Dream Pal request. The other player's footprint mat will then glow until the request is accepted, deleted or expires. If the other player accepts, the two players become Dream Pals, and a rainbow bridge will link the two players' homes on their Dream Pal maps. Dream Pal requests last only a week before they are automatically deleted. There is a limit of 20 Dream Pals (including pending Dream Pal requests) per player.
When visiting another player's house, it is possible to view their Dream Pal map, and go directly to the houses of other Dream Pals of that player. This allows the creation of large networks of players.
In addition, on the player's Dream Pal map, a random player's house will appear in the bottom right-hand corner, as long as the privacy settings are set to "everyone". This player is randomly selected every time the player opens the Dream Pal map.
Prior to the April 2011 update, Dream Pals were only those that players had added to their Pal Pads."
- Bulbapedia
