The Yu-Gi-Oh! anime's Battle City arc is without a doubt the best in the series. It is full of nonstop action and fantastic duels. Despite being done incredibly dirty by the writing and plot armor this season, Mai Valentine was a standout character in this season of the show.
Mai's deck is full of interesting and powerful cards besides the standard Harpie Lady monster that viewers had gotten to know in the prior season. Some of these cards stood above the rest as being incredibly powerful. The following cards are in no particular order.
Cyber Harpie Lady
Cyber Harpie Lady is an upgraded version of the original Harpie Lady, having a much more respectable 1800 attack points over the usual 1300 that a normal Harpie Lady has as if a Cyber Shield is already equipped to the monster from the word go.
Unfortunately, this is the only effect that it has, making it a weaker choice than a monster such as Harpie Lady #1, which powers up all Harpie Ladies on the field, rather than just Cyber Harpie Lady.
Amazoness Chain Master
Amazoness Chain Master is a card that, upon destruction, allows the player to pay 1500 life points in order to take a monster from the opponent's hand of their choice.
This is the card that Mai Valentine used to take The Winged Dragon of Ra from Marik's hand. This should have been a winning strategy for her, and it was a great play. Unfortunately, plot armor wouldn't allow for her to defeat the villain of the season.
Harpie Lady Sisters
Harpie Lady Sisters is not a good card in real life. However, the girls work differently in the anime, as the sisters operate as different monsters, meaning that one set of Harpie Lady Sisters is three monsters, which provides many more benefits than one monster with 1950 attack points.
Using Elegant Egotist to summon her Harpie Lady Sisters is actually how Mai brought out The Winged Dragon of Ra, as they all counted as separate tributes for the monster.
Mirror Wall
Mirror Wall is a frequently used trap card of Mai's, and it can help her out of many tricky situations. The card can be activated while being attacked, and it slashes the opposing monster's attack points in half.
This is also a continuous trap card, meaning that the opponent will either be forced to deal with the card or have their monsters lose half of their attack points every time that they declare an attack.
Amazoness Fighter
Next in Mai's camp of powerful women is Amazoness Fighter. The card has 1500 attack points, which isn't much, but any attacks involving this card will not result in battle damage for the owner.
Put simply, this is an easy card for Mai to throw out without needing to worry so much about battle damage if it were to be destroyed.
Gravity Bind
Gravity Bind is a trap card that, when activated, stops all monsters that are level-four or higher from attacking. While this doesn't exactly put Mai at a major advantage or anything, it can be a very useful card to help shut an onslaught down before it is destroyed.
All of Mai's monsters would be affected by this card as well as the opposing monsters, but this is still a very useful card to keep her safe in the case that she draws a few useless cards back to back.
Elegant Egotist
Elegant Egotist is the card that Mai Valentine always uses in order to bring her Harpie Lady Sisters out onto the field. As long as she has one Harpie Lady on the field, she is able to triple it into three monsters by using the effect of Elegant Egotist.
This easily makes Elegant Egotist one of her most powerful cards, as being able to bring out two different monsters onto the field with no downside is very powerful.
Harpie's Feather Duster
Harpie's Feather Duster is another one of Mai's most powerful cards, being able to wipe out the opponent's entire backrow with absolutely no downside.
In fact, this card is so powerful that it was banned in the real-life card game until very recently, and still sees a huge amount of competitive play. Mai certainly knew what she was doing when it came to crafting a balanced and powerful deck.
Graceful Charity
Graceful Charity is a card that allows the player to draw three cards as long as they discard two from their hand.
Considering that this card generally has the same amount of power as Pot of Greed, it makes sense why Mai used it in her deck. Drawing cards is one of the most powerful effects in the entire Yu-Gi-Oh! card game.
Dramatic Rescue
Dramatic Rescue is a card that Mai can use when any of her Amazoness cards are in trouble. It allows her to return the Amazoness that has been targeted back to her hand and summon a new monster in its place.
This allows the original Amazoness to stay safe while also ensuring that the player doesn't lose any momentum in the switch, allowing a monster to replace the Amazoness right away.