Man this is sooooo freaking simple. It's all about strength. Since in one of those alternate universe thingies Juggernaut is a member of the X-men now. I would choose him, Colossus, and wolverine. Just picture the combined might, invulnerability, leaping ability twice as effective as the hulk's of juggy and colossus. Then factor in Wolvie's adamantium with colossus's organic metal, then add 1 healing factor with the near impregnable force field juggy generates around his body, plus that trusty helmet of his that ward off psi attacks. Lastly, mulitply that by the fact that all by himself juggy was practically immortal; having no use for food air or water. And the fact that in metal form colossus also had no use for food air and water. And the fact that with his healing factor Wolvie could easily out live the entire human race if he stays out of harms way. What we would here have people is a being who is truly undefeatable in every way. Only a being with reality warping powers like Proteus, X-man, Phoenix, or Franklin Richards or any number of those abstract cosmic entities like death, oblivion, destiny, eternity, infinity, order, chaos, or Kismet could pose a threat.