How to Recruit Shelley - Dragon Quest 6
Shelley is one of the optional slimes that players can recruit in Dragon Quest 6. In order for Shelley to join your party you'll need to have recruited Curie, a healslime first. To recruit Curie you will need to either trade enough dreams with another player or complete the game and speak to Curie at the Suite Dreams in post game. For more information check out my guide specifically on how to recruit Curie the optional healslime.
Note: She is not available in the SNES (original release) of the game; only in the DS and Mobile remakes are you able to recruit him to your party.
Once you have Curie, you can find Shelley in the Real World at the Underwater Inn. The fastest way to reach this location is to Zoom over to the Fashion Forge and get into your boat then use Lorelei's Harp. You'll find the entrance to the Underwater Inn just north of the Fashion Forge.
Underwater Inn Map Location (north of Fashion Forge).
Vocation Permanent Rewards
These are the passive & permanent rewards that you will get when mastering a Vocation. You'll keep these boosts even when switching to a different Vocation. Once you reach level 5 in every Vocation you'll receive a Gospel Ring from the priest in Alltrades Abbey as well which will allow you to avoid encounters. You do not need to reach level 5 in every Vocation on 1 character, it can be done on multiple characters.
Gladiator: +20 Strength
Armamentalist: +20 MP
Paladin: +20 HP
Sage: +20 MP
Ranger: +20 Agility
Luminary: +15 Style (or 20)
Hero: +40 MP
Dragon: +20 Strength
Liquid Metal Slime: +100 HP