Go east of there and into the Amusement Park. Continue east, and you'll find N in front of the ferris wheel. He offers you a ride. As you ride on up, he divulges some details about Team Plasma, primarily that he is their leader. The ride soon ends, and N battles you so as to let the nearby Grunts leave.
Team Plasma N
Pokemon:
Sandile (Lv. 22) Ground/Dark
Darumaka (Lv. 22) Fire
Scraggy (Lv. 22) Dark/Fighting
Sigilyph (Lv. 22) Psychic/Flying
Type Weaknesses and Immunities:
Sandile is weak to Water, Ice, Grass, Fighting, and Bug. It is immune to Electric and Psychic.
Darumaka is weak to Water, Ground, and Rock.
Scraggy is weak to Fighting, Bug (maybe), and Flying. It is immune to Psychic.
Sigilyph is weak to Dark, Ghost, Electric, Ice, and Rock. It is immune to Ground.
Recommendations:
Your simian and your starter at Lv. 24+. It is a full guarantee that at least one of them will have an advantage over Sandile. It is possible that if you lack a Tepig/Pignite, you'll also have the advantage over Darumaka (if not, use your Tepig/Pignite). As for the other two to fight, your starter should be able to deal with both (unless it is Grass, in Sigilyph's case; switch to Pan/Simipour if it is so).