You can use the Mixtrack Pro with Serato DJ Intro OR Serato DJ if you purchase the $129 license.
serato.com You can use the SL2 with SSL with either but you will need players or something to control the decks with as you can not map the mixtrack to SSL.
May I ask what made you think you can't use the Mixtrack in Serato DJ?
That being said I noticed you said before I purchase a new controller and TBH i would suggest exactly that. The mixtrack is great for beginners and the Vestax was great in its day and is still great in the analog world but coming from traktor you may find yourself feeling limited. Don't get me wrong with Serato DJ you will be greatly pleased and IMO (as a user of Traktor, Rekordbox & Serato) is much better in terms of getting your ideas to your crowd but you need the right tools and in all honesty without performance pads you just won't get the whole SDJ experience so the obvious answer would be looking for a controller with performance pads.