Pokémon Mystery Dungeon: Blue Rescue Team and Red Rescue Team/Joyous Tower

Joyous Tower is one of the level one dungeons in the game. When you enter, all of your Pokémon's levels are downgraded to level one temporarily (all higher level moves are forgotten temporarily, too). When you leave, they return to normal. Similarly, when you enter you will lose all of your money, so put it all in the bank before entering. Before entering you must save the game, so make sure you have an Escape Orb.

This dungeon gets added to your list after saving the Latias duo and acquiring the Sky Blue Plains Friend Area.

There are 99 floors in this dungeon, but there is no need to explore them all. The only two reasons to come to this dungeon is to recruit the exclusive Pokémon found here and get the Friend Bow from one of the Kecleon shops (it appears randomly in the shop inventory).

Items
Do not hesitate to bring in items that will be helpful to you, since there is no guarantee that you will find all of the items you would need just lying around. Since the greatest reason for coming here would be to recruit certain Pokemon, Escape Orbs are highly recommended so all of the hard work recruiting said Pokemon isn't wasted. Also bring a few Reviver Seeds in case of an unfortunate turn of events, and possibly a Joy Ribbon/Tight Belt, along with a few Huge Apples, to increase your chances of survival.