Where do you get Jynx in Pokemon HeartGold?

In Pokemon Mystery Dungeon: Blue and Red Rescue Team, Jynx is only obtainable through the evolution of Smoochum. Smoochum can be found in Joyous Tower between the 21st and 25th floors. Once Smoochum reaches level 30, you are able to evolve it.

In Pokemon Mystery Dungeon: Explorers of Time and Darkness, Jynx can be found in Crevice Cave from the 1st to the 10th floor. It may also be evolved from a Smoochum, much like in Red and Blue Rescue Team.