I believe the tests are comparing the valueOf Card objects.
(I don't feel bad revealing this information because it should really be given with the kata, but feel free to mark as a spoiler.)

Could you elaborate on what it means to be Comparable? There is no information on what elements are being compared, or what the expected output is. The tests that fail because of this give no useful information, unfortunately.

Did you change your code, or did the method mysteriously start working? I'm still getting NoMethodErrors for Array#any? and Array#all?

I think eql? returns true only if the two arrays contain the same content. We're supposed to be checking if the numbers in the passed in array are seen in the current array. So a passed in array of [1,2,3] should return true for a current array of [0,1,3,4,2], since 1,2 and 3 are commmon to both arrays. However, both arrays do not have the same content.