There's a little Irish bar in
Schoneberg with a darts room attached. The name escapes me, but it's in Apostel-Paulus Strasse, which is tiny, so easy to find...basically 30 seconds away from the Eisenacherstr U-bahn stop, on the blue U7 line. Apostel-Paulusstrasse is behind the big church. It's nothing fancy, but friendly enough. A small pool table also.
A really good pool table - can be found at another bar in Schoneberg, at the intersection of Nollendorfstrasse and Eisenacherstrasse. The bar is called HeckMeck, a really good spirit in there, it's been going for about 30 years, really good mix of people. Best bit is it has a huge pool table, in its own room, and not too busy. Good atmosphere. During the daytimes it's easy to monopolise the table and have a big pool session! At night-time pool is played, beer flows, new friends are made easily. Check it out.