Dreamyard

Arriving at Dreamyard again, you will see the tree from before. Teach a capable Pokemon to use Cut. Sadly, you cannot use a herring, as this is not the mightiest tree in the forest. Chop down the tree with Cut. As you progress, Bianca arrives and asks if you are looking for a mystic Pokemon. She steps aside. Attempt to advance. As you walk ahead, you hear a Pokemon. Go straight ahead. There is a Pokemon here. The Erotic Sage's Playmates (Team Plasma) show up and reveal the Pokemon as Munna. They want to use its Dream Mist to promote the PETA, and then contradict this by abusing it. One of them approaches you, and you proceed to defeat him.

Team Plasma Is Up To No Good!
You will be facing a single Patrat at Level 10. This fight is easy street. You get a measly 400 PokeDollars.

Right after that, the second grunt wants to fight. She uses a Purrloin at Level 10. Once again, winning is easy.

After winning, the grunts go back to abusing Munna. Just then, Ghetsis arrives. Twice. The Erotic Sage is up to something. He scares off his grunts, and Musharna appears and begins treating Munna. It turns out that Ghetsis was a result of Dream Mist. Bianca suggest you find Fennel. In this back area, you can encounter Munna. It's a Psychic type, which means two things. You can either catch one (but to be fair, it's slow and hits weakly), or you can train up Dark types in particular. There's a Pokeball in the grass to the west.

There's another Pokemon to look for. Walking around, you may notice shaking grass. If you step into it, you will fight Audino. Audino can be caught, or you can defeat it. The experience gain is massive, so keep that in mind as this a superb training option. You can level your Pokemon roughly 6 times faster by fighting Audino constantly. Go find Fennel when you're ready. She'll give you the C-Gear! Head to Route 3 to the west.

Go to: Route 3