Disgaea 2: Cursed Memories/Specialists

Subdued specialists can be moved to different items.

Status Effect Modifiers
(all status modifiers max out at 100)

Bonus Specialists
As a general rule of thumb, it is a good idea to subdue and collect these bonus specialists early and often. All four specialists help reduce the amount of time needed to increase your party's strength, especially once you get to the point where you can create lots of new and fancy character classes. Note that the Broker and Mentor specialists do not affect bonus gauge gains or treasure chest box rewards, only kills.

Dual-Stat Specialists
(all dual-stat boosters max out at 1999)

These specialists are created by the Mediator Specialist. Unlike regular stat boosters, these specialists do not enhance item stat gains during level ups! So don't leave them on items when going into the Item World.

Collectors
Collectors are interesting, if not so useful at first. The best use for collectors is to make several items of matching rarity value, so that your character gets the rarity bonus when equipping them. Note that these specialist actually increase the rarity value, which effectively decreases the actual rarity of the item. If an item has a rarity of 17 and you install a collector of value 1 on it, it's rarity value will become 18.

Collectors are obtained via the random rooms that you find in the Item World. If you stumble upon one, he will ask you if he is welcome to join your item, and will be subdued if you say yes. ''[research needed: the collector room may only occur on items that have open specialist slots? And if not, what happens when a collector joins an item that is already full?]''

Mediator
A Mediator works by appearing in the Innocent Town of an item that it's on, and marrying two regular specialists into one dual-stat specialist. The chance of this happening depends on the level of the Mediator [confirmation of a precise formula needed needed]. The resulting dual-stat specialist is usually, but not always, based on the original specialists -- A Marksman and a Gladiator will usually, but not always, be married into a Sniper. The level of the resulting dual-stat specialist will be based on the level of the item and not the levels of the original specialists! So when using Mediators it is always best to use small specialists on high-level items, such that the resulting dual-stat specialist will actually be much more powerful than the specialists used to create it.

For the marriage to work, the item in question must have an open specialist slot available, and the newly-created dual-stat specialist will have to be re-subdued.

It seems like a lot of work and, well, it is. Early on I'd suggest collecting these guys and keeping them on a few unused items in your warehouse, but not using them unless you really need to for some reason. Still, items in Disgaea 2 have only half the number of specialist slots of it's predecessor Disgaea: Hour of Darkness (3 or 4 normally, and 8 max), so slots space can become a premium especially later in the game.

Teacher
Teachers work similarly to Mediators, in that they have a chance of appearing in the Innocent Town of the item they're on and, if present, will 'educate' another specialist for a 5% increase to its level. The level of the Teacher affects it's chance of appearing in the Innocent Town only, and does not affect the level increase (which is always and exactly 5%, rounded down [confirmation needed]).

Example: Dietician/50 getting a Teacher bonus of 5% will be upgraded to a Dietician/52.

So again, much like the Mediator, the usefulness of this specialist early on in the game is neigh. You're only going to find yourself wanting to dabble in the affairs of Teachers if/when you get to the point of having specialists in the 500+ range, so that dancing through a half-dozen Item Worlds hoping for a Teacher's appearance doesn't feel like a big waste of time. And who knows, even then it might.

Lovers
Lovers are a unique brand of specialist that auto-magically spawn on weapons that a character has used for a certain amount of time.