In a random encounter, I'd say Wolverine has a slight edge. 6/10(it would be more with pre-52 Slade)
Give Slade basic information about Logan, and a little time to formulate a plan, and the odds go in Slade's favor. Again, since Slade's strategic/tactical skills seems to have been nerfed, while his actual combat skills have been boosted, in the 'new' 52, it would be more(in Slade's favor here) with pre-52.
"This one is a bit inaccurate, not potentially limitless power, but limitless potential for development, and that's it."
After re-reading it, it seems that we're both off about the only official requirement.
It was given by Xavier, and is simply "unlimited potential". The added "power"(by me) or "for development"(by you) is purely a fan thing, and not something official.(X-men Forever #3, from 2001).
"According to Xavier he does."
Not quite. According to Xavier, even Magneto himself doesn't realize his true potential or limits. Unknown limits/potential =/= Unlimited potential. And the very fact that he is limited by his physical condition(as officially stated) means that neither his power, nor his potential, is unlimited.
"Neither can Hope, Vulcan, Franklin Richards and few others, thus being able to overcome physical body is not what defines an omega level mutant."
Hope is a power mimic/copier, she can copy the powers of someone who overcome the limitations of their physical bodies. So while it's not a direct part of her immediate power(s), yes, Hope is capable of doing it.
Vulcan can also overcome his own physical limits. As demonstrated by his ability to manipulate the energy forming the matter of his own body, both for healing and for self-sustenance(removing the need for air, food, etc.).
Franklin is a telepath(thus having at least the potential for simply leaving his body), and a reality warper.
Literally the only confirmed Omega, that hasn't demonstrated having some way of overcoming the limitations of her own body is Maddie, a teleporter that only appeared in 3 issues of Deadpool vs Old Man Logan.
So while it's not an official requirement, the evidence is strongly in favor of it being one of the requirements for the classification.
1. Marvel hasn't had a reason to put an Omega-level classification on him so far.
2. The various power and/or threat level classification(in-universe) comes from a bunch of different sources, with none of the criteria for any of the sources having been actually published. And none of those sources have been seen giving him an Omega-level classification(so he would, at best, be an unconfirmed Omega).
3. The one, and as far as I know only, requirement for "Omega-level" that we have been told is "potentially limitless power", which Magneto doesn't have. His power is limited by his physical condition, and unlike the majority of confirmed Omega-level mutants, he is unable to 'abandon'(for the lack of a better term) his human body to overcome those limits(like Iceman taking on his ice form, various telepaths leaving their bodies, etc.).
There might be more reasons, but those are the ones that immediately spring to mind.