Is it possible for a sales person to sell anything and what skills should he have?

Thank Hamid This is a good answer, but in my opinion that the specialist sales person is the best

Yes, Selling is both Science and Art. We can sell anything to anyone if we become "A Financial Improvement Specialist".

the good sales persons can sell what ever IF they have the good knowledge about it and if they love it

Sales is about selling a product to someone, I feel sales at the end of day is a art in itself.
If the salesperson is given a brief and knowledge about what he is offering to the client & is able to pinpoint his target segment then yes a same sales guy can sell multiple products to clients.
Main skillset required should be as: 1.
Confidence 2.
Product Knowledge 3.
Able to understand client requirements