Teenagers are like other people: individuals. With their own individual strengths and their own individual problems. Yes, there are brain changes and hormone changes which can exacerbate odd behaviour- but then you could say the latter about the menopause too.
(I was a teenager at the same time as my mother went through the menopause and I can tell you, whoever behaved like a teenager in our house it wasn't me... Thirty years later, I am going through the menopause and it doesn't seem to leading to many mood swings, so maybe I'm just not sensitive to them.)
My own teens so far:
dd (17) has suffered severe anxiety all her life and been prone to mood swings (very like my mother). She got worse during her early teens. But she has always been a pleasant person in herself, well spoken, with a great sense of humour, empathetic and willing to understand other people's pov. That's clearly who she is and the teen years made no difference to that.
ds (13) got noticeably more moody during the pre-teen years and more prone to challenging authority. But also a kindly person who supported his sick sister, made friends at school and was polite to teachers. Having now gone through puberty, he is noticeably happier and more at ease with his new-found maturity. He has learnt to use humour to diffuse awkward situations and is getting very good at negotiating without hurting people's feelings. Looking good so far.
So far my teen isn't difficult but she's only 14 so there is plenty of time for things to go wonky. Her room is clean, she has been doing music practice and voluntary extra homework unbidden each morning this week and has been helping me with a big project cheerfully so that in the afternoons her time is her own to game or be with friends and what not.
I do wonder if this will bite me on the bum in a year or two?!