D/D Haku? As far as red subs go, another D/R Haku, Echidna, Persephone, and uvo Hadar are the only ones I can think of.
Blue? D/B Vampy, Hera-Is, and non-uvo Beelzebulb are good, as is Loki.
Want dark rows? Pandora, Gryps Rider, Dark Metatron, uvo Hadar and Lilith are good. You could grab ult Zaerog for a gravity if you can handle the negative RCV.
Want to two-prong it up? UVO Beelzebulb, Thoth, Chaos Dragon Knight, Dark Fagan, Dairy Queen Hera, uvo Hadar and Gryps Rider got your back.
Got a Lu Bu available? Grab that uvo'd Folklore for massive burst when you need it.
(This is considering the uber balancing that NA probably won't see for a while, but yeah)