Pokémon Diamond and Pearl/Route 214

The person in the gatehouse on the Veilstone City side mentions this place as a "mess". However, there are some thing to look around here, as well as many trainers to fight.

Ruin Maniac Cave
A Ruin Maniac is digging away in the mountain. Pick up TM28 (Dig) and talk to him. He proposes a contest where you catch Unown and he digs away. Catch 10 different kinds of Unown to find the tunnel much longer, and catch all 26 to discover he has plunged through into Solaceon Town and into a room wiht the last two Unown, ! and ?.

Items

 * TM 28: Dig