You forget that the Ultimate versions are a lot weaker excluding Magneto who is not too far off his original incarnation (although still not much to current Mags). Juggernaut is just a strong teenage weapon x-er, Sinister has no powers and Apocalypse is part hallucination, part mannequin with earmuffs (I put him in to egg Sinister on).
Wow. A sabretooth with adamantium, a Magneto who is pretty close to the current one (I believe), and Juggernaut?? Magneto himself could insta-kill everyone with the exception of Plastic Man and Black Canary (and they only survive in this scenario because I don't know if they routinely carry anything metallic around) and the rest ot the villians could easily ahndle those two.