Teams we can essentially rule out as competition for Brooklyn's worst team status:
Boston
Toronto
Cleveland
Milwaukee
Detroit
Washington
Miami
Charlotte
Golden State
LA Clippers
San Antonio
Houston
Memphis
Utah
Oklahoma City
Portland
Denver
Minnesota
Teams that are highly unlikely to be as bad as Brooklyn:
New Orleans
Dallas
Philadelphia
That leaves us with the following teams:
New York - As dysfunctional as they might be, I find it hard to believe that a team with Porzingis and Carmelo are a worse team than Brooklyn.
Indiana - We'll see how the rest of the off-season plays out, but Oladipo and Turner don't seem like the makings of the worst team in the NBA.
Chicago - If they buy out Wade and LaVine isn't healthy, they're a legitimate contender for this spot.
Orlando - I'd definitely put Fournier, Gordon, Vucevic, Isaac ahead of Brooklyn.
Sacramento - Much improved. Some sneaky potential to fail if Randolph loses another step, but I highly doubt they are that awful.
LA Lakers - The Lakers with Lopez and Ball are almost certainly better than the Lakers with Russell, and some growth should be expected from Ingram.
Phoenix - Growth from Booker, Bender and Chriss, along with anything Jackson contributes should lead to a better Suns team, but I wouldn't rule them out.
Overall, I see really only 2 or 3 teams that seem to truly have a great shot at being worse than Brooklyn.