its the player's choice to put aa guns (with aa gunners of course) on their bb5/6, or just put 2 reps on t slot and run without AAs... you could see alot of bb5 in the game without aa guns if your looking around

its mostly players choice

but if you gonna play with the ijn bb4-5 i do suggest you use AA guns on it aswell as km

those 2 are really good with AA guns ;)

Yes you can do well in a bb5/6 without AA guns.

You can entirely focus on your aiming and let your teammate's CV to do the air cover for you.


But...but... if your FW teammate CV is dead and your opponent bb5/6 has got nice AA, you won't stand much of a chance unless your opponent is noob. 

While carrying AA guns increases your general ability to deal with aircraft, and you can be more independant as a result and not having to rely on BW's and noobs in the CV section. However if you leave those T slots empty that works too, and in some cases you can actually keep speed if you don't. Just be ready to dodge dive bombers and be spotted if there are no AA boats nearby... But choosing not to do so is not a bad decision, as many players will do it regularly, and you won't get called out as a noob in BB4-6 if you don't have any. 

Here are my 2 cents

USN:
They have useable AA but are good without it too.

RN:
Most players use them without AA guns. Though they have those very funny pompoms that are very deadly for camping fighters and bombers. But they really don't need AA gunners. Maybe use 1 gunner/torper/aagunner for some HHs on the t-slots to defend yourself against subs. Especially when you run UK as AW you will have no bulge and run just 35 knots on QV.

IJN:
Sorry, can't help you with IJN

KM:
This nation really should be used with AA. They have the best allround AA making the grind a lot more enjoyable. Furthermore its range advantage allows KM to dodge a lot shells and therefore doesn't relies as much on repairerate.

MN:
Have 2 sets of good AA guns. One with godlike range (my recmommendation) and one with a lot of firepower but lacking range and reload. But MN tends to rush a lot and catch a lot of shells. So running MN with or without is okay.

SN:
5.1inch dual SD guns are the SN AA guns of choice. Not as good as IJN aa guns but still good ones. SN has many BBs that allow you to run faster when using no t-slot weapons. Its BB6 can be pushed to 37 knots with light crew. If you want to go 37 with BB6, 39 with BB5 and 42 with BB4 better go with no AA. Therefore I recommend to run SN without AA.

RM:
They have no real AA guns. But maybe consider getting 1 high lvl Gunner or torper to use HHs on half the t-slots.

ijn has good aa (4.7's my favorite)

but niborger probably doesn't have a ijn line, which would be why he can't advice on them