What is an A and S rank?

An A or S rank is either your POW/Tec ranking and you get them by winning duels. Pow rankings are how quickly you defeat someone. A Tec ranking is how low a number there Deck is when you beat them.

They are ranks that you get by how well you do in a duel.
To get them just beat your opponent in only a couple or few attacks
Hope this helps :D

Alright man, here comes your answer.

The A and S ranks are the elite records in a duel. Only appears if you kill without mercy.

First, get a killing deck: full of strong cards. (I reccomend using a deck with nothing but thunder and dragon monsters and cards that power them up. I have this game for a year and I now have the ultimate deck - ONLY 5 STARS!!!)

Now, fight somebody of your level. Or somebody weaker. Start summoning the strongest monster possible in your hand, leave it in attack position, or maybe in face down position also in attack mode. (your opponents always attacks if it is unknown) On your second turn, summon another killing monster, hit his/her cards and life points. He/She will summon again. Devastate his/her defense and kill her. It is that easy.

Hope I helped you.

Sincerely,
Blue Eyes Magician.

A and S ranks are how well you have either defended or attacked. You can get power A for attacking or defence A for holding out when defending. By attacking and winning decisively you get a A rank.

S rank is followed by A rank.S rank give y 5 SChips and and A rank gives you 4 SChips. The best way to get S Rank you shoul bring the LP of your opponent to zero using 8-9 cards.And if you win by reducing opponents cards to zero then you get S Rank.
I HOPE THIS ANSWER SATISFIES YOUR QUESTION