Edit: after writing that huge wall of text I realised that it might be a an unwanted thing to read, but I didn't want to just delete it lol
So TL;DR: Usually black tea is used for milk tea, but there are different kinds of black teas and he might not be as good as others as milk tea
@_Captain_America_or_CAP @ketchupforblood there's even different kinds of black teas though! Not even delving into herbal, red, or green teas...
I think assam is wonderful as milk tea, and ceylon would be a second best, but I don't think oolong works as well as those two (even though some people do enjoy it, it's just more of an acquired taste I think).
And those are just the simple black teas, once you get into blends (Earl Grey, English Breakfast, chai, all REALLY GOOD as milk tea), there's even more options! I enjoy black teas that are good for milk tea though, so I tend to stick with blends that do. Off the top of my head I can't think of a blend that isn't as good or better as milk tea.