KO have very limited ally options. Ironweld give KO nothing. Disposessed give them cheap screens and magic defense, which if you want to run a foot based KO army, you 100 percent require. Fyrslayers give slightly more mobile screening and striking, though they nerfed the combo of smiter and zerkers to make it harder to pull off.
And then there is SCE. And they're SCE. Only way to play with magic. Character to buff ships. SCE support KO almost better than KO characters can. THe Khemist is the only one that comes close.
But there isn't an army you can build that you can use to beat a good player with a meaner army. It doesn't matter what you toss in, someone with skill playing a tournament nurgle army, or just deepkin in general since they are the ****** KO army, you will loose 9 times out of ten and the tenth will be dice skew. So there's no point throwing together allies to make your army competitive, because they won't. Put them in if you want, but there's no real pressure to do so to win, because it doesn't help. You're still just playing KO.