Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness/Chapter 17: The Guild's Crew

You'll have to travel with Chatot he is lv34 this dugeon is easy with lv34 and lv35 Pokémon at the end of dungeon Kabutops and two Omastar attack and Chatot shields you, battle and then you are done with the dungeon and meet Lapras.
 * Brine cave
 * Difficulty 5
 * Boss Omastar(2) and Kabutops

You can not recruit any Pokemon 'till after credits.