The Outcasts are a collection of models that don't really fit anywhere else, and as a result, their playstyles tend to vary drastically from one Master to the next. As a whole, the Faction has a fair number of ranged attacks which is balanced against some very good melee models. Many Outcasts are also Mercenaries, which allows them to be hired into the crews of other Factions at a slight increase in their cost.
The Outcasts tend to mostly use Living models, but a number of Masters can hire Undead into their crews as well, so it's not uncommon to see the Outcasts borrowing some Resurrectionist models from time to time. Because their Masters are so unique, many of the models are thematically built around supporting one Masters, which can make it difficult to get much use out of them in crews led by other Masters. Most every model with the Mercenary Characteristic is generically good, however, making them solid additions to just about any crew.