the first skill, the skill that any self respecting ml gotta possess is IMPRINTING 

your job as an ml is to IMPRINT on your lover so hard that no matter how he looks, no matter how he acts, and no matter the situation, you would ALWAYS know he is your lover.

he can turn to a girl, find him! 

he can become an ai, identify him!

he can turn into a mythical beast, search for him!

he can be the person you always hated, the one you never payed attention to before, DO NOT ELIMINATE ANYONE !

your wife can become anything, even your own brother which you grew up with for years yet never felt special before.

it is the job of any self respecting, any worthy ml to recognize his one and only, at all circumstances and situations, behind any mask, and in any sort of form and shape. fail at this and you are UNWORTHY of being an ml, as he would simply slip away from you in the next life. following him means absolutely nothing if you don't know who he is!

now for ml doubters. what? your first skill is your manliness? your charm? an endless amount of stamina? a way to make your mc swoon? an extraordinarily strong soul, enough to make you capable of following your mc? BZZZT ! all wrong, those are all some bonuses.

the mc can find many ways for you to follow him, himself. which i'll talk in the next chapter. you can do so in many different ways, you DO NOT have to get powerful souls for this. those are bonuses. stamina and charm is dependent on your body and role in the world your in. it would be very much possible to start in a world as a child, or sick person, and only grow stronger with your lover help. at those times, you no longer have this 'amazing stamina' of yours .

now, the reason why i believe any true ml first skill is imprinting, rather then being 'the ultimate golden thigh' or anything of the likes, is that some ml had started by being the 'cute type'. most ml had a sad or empty life and by the mc SAVING them, at least in their eyes. they IMPRINTED on them. later, they grew up to be the strongest mainly in order to protect their mc, and only then became 'manly', with the IMPRINTING already intact. yes, you may be manly, strong, and 'the best' in your world even before you met your mc and IMPRINTED on them, but you were not the ML until after you did.

that is why, beginning ml, forever remember, IMPRINT on your lover, recognise him, and find who he is first, and where, sometimes when. you just CANNOT begin the chase without it. as you just can't chase what you can't find.