I have only ever seen one deck aimed at teens that I think works, and its OOP now and very hard to find indeed.
This Witchy Tarot is one that I think is very demeaning to teens (I agree largely with inanna_tarot here). It doesn't even do a very good job at translating traditional Tarot into a teenager's language, but instead bombards us with scantily clad big-breasted young witches who only ever seem to think about looking glamourous, checking out the cute guys that appear every now and then on the cards, and casting spells. It's not realistic enough to relate to a teen's world.
I don't see anything wrong with giving a teenager a traditional deck. There are some lovely RWS-style decks such as the Robin Wood, Universal Waite, Sacred Rose, etc that are aesthetically pleasing to young people, colourful, vibrant, easy to read with, etc. The Witchy Tarot tries to hard to fit the Tarot into its theme that much of the Tarot is lost - witness the Court Cards which I would find almost impossible to read, compared to a traditional Tarot with traditional Court Cards that I find very easy to read.
Furthermore (okay, I'll be done in a minute) another reason (I think) for getting a more traditional deck for teenagers and beginners is that there are more books out there that apply to those decks. Take Kate Warwick-Smith's wonderful book "The Tarot Court Cards: Archetypes Patterns of Relationship in the Minor Arcana". It's a groundbreaking book, looking at the Court Cards in an innovative, non-clichéd, and helpful way. But anybody trying to apply the Witchy Tarot's Court Card system to it would find themselves inevitably lost and confused. Decks like the Witchy Tarot don't translate well onto other decks, so when one wants to use a different deck, one virtually has to start all over again!
Okay, I'm done.
Kiama *Not a fan of the Witchy Tarot!*