It's inevitable sometimes that a FC will have to take out a kitchen sink fleet, everyone having a different special snowflake ship and fit. Sinkfleet is an attempt to impose some uniformity so at least the ships all do the same thing.
What thing is that, you ask? Brawl.
The reason for brawling is there's no point having snipey battlecruisers off doing 200 dps when each enemy ship is in our face doing 700 dps. Every ship counts and the simplest job to give a generic mixed collection is close range damage.
So here's the doctrine:
High slots close range weapons, (optionally neuts). Close range faction or T2 ammo.
Mid slots: web, scram, microwarpdrive,
Low slots: at least one weapon upgrade (eg a heat sink),
In addition try to fit a tank consisting of Damage Control II, and either Shield Extender plus invuln or EANM plus plate. Shield extenders and plates should be oversized if possible (eg a LSE on a cruiser, a 1600 mm plate on a cruiser).
Include drones, damage drones ideally Gallente Tech 2 drones.
Use any left over slots to increase 1) speed and 2) damage in that priority order.
The role of this fleet is just to nuke the crap out of anything it can catch. It's not recommended that anyone bring anything subtle like logistics or ewar, just all come in gank ships and kill them before they kill us.
It's also possible to make sub-doctrines, eg Destroyer sinkfleet, T1 Cruiser sinkfleet.