With well over ten thousand cards, not every one of the tools players have access to in the Yu-Gi-Oh card game is good, most of them aren't, in fact. It takes a very specific set of abilities for cards to see use in a competitive capacity.
Yu-Gi-Oh! 10 Cards That Used To Be Bad, But Are Now Great
The rules of Yu-Gi-Oh! are always changing and the card game is constantly releasing new cards, often changing the importance and power of old ones.
That being said, the rules of the game shift dramatically from year to year, and with new cards constantly being added the potential for never before seen combos grows exponentially alongside the trading card game. Here are some examples of Yu-Gi-Oh cards that were mostly useless when they came out before they suddenly weren't.
Back when it was first released, like with many of Jaden Yuki's Neo Spacians, Aqua Dolphin was considered a joke of a card, it's ability had a great payoff of destroying cards in your opponent's hand but it was too weak on its own and the potential drawbacks of its ability were much too high.
Now though, most decks play at least six or more low-level monsters with no attack points at all, making Aqua Dolphin uniquely skilled at picking apart the opponent's hand before they even have a chance to use it.
One of the titular Signer Dragons from Yu-Gi-Oh 5Ds. Ancient Fairy Dragon's strange effect that let it destroy field spells in order to search out a new field spell from the deck. With the rise of link monsters, it became quickly apparent that what was once an acceptably powerful monster could become a serious problem.
As field spells like Union Hanger, Dragon Ravine, and Golden Castle of Stromberg became much more important, Ancient Fairy Dragon had to be banned because of the insane potential it held.
Part of the strange Mecha Phantom Beast archetype, this group of cards have several powerful members but struggle to actually work together like a deck should. Thus, O-Lion was overlooked early on during its 2014 release.
However, with the growing relevance of both synchro monsters and cards that produce tokens, O-Lion suddenly ended up back in the spotlight as a key card in many strong decks thanks to its ability to create tokens when it's sent to the graveyard, meaning a monster that uses O-Lion as a tuner can then use the token to become an even bigger synchro.
Compared to some of this list's other entries, this synchro monster isn't as terrible. It certainly could help with the few synchro monsters that required two tuners to summon but that was hardly enough for it to see any play.
Combined with the strength of the previous entry's ability to summon tokens, however, Martial metal Marcher and Mecha Phantom Beast O-Lion formed a powerful combo to get powerful synchro monsters like Borreload Savage Dragon onto the field faster than ever before.
6. Rainbow Neos
Another Neo-Spacian finding it's way onto this list. Rainbow Neos was a fusion monster that rather specifically needed the fusion of Elemental Hero - Neos and Rainbow Dragon. It's abilities were very powerful but the problem was that there was really no reason to play Rainbow Dragon in a Neos deck, it'd just be dead weight.
Over ten years after its release, the cards Neos Fusion and Predaplant Verte Anaconda have made Rainbow Neos a threat to be reckoned with in any Neos deck -- since they can search out a Rainbow Dragon from anywhere in the deck for a fusion summon, finally giving this card a home.
A niche and amusing card, Double or Nothing! let players double their monster's attack points and attack again, but only if a card effect negated their first attack. The obvious choice is to use it in a deck themed around Number 39: Utopia, like transpires in the Yu-Gi-Oh anime. But it's still a pretty situational card. That is until Number 39: Utopia Double came along and let one pull Double or Nothing! from their deck at little cost.
With a single copy of Utopia, Utopia Double, and Double or Nothing!, any deck with the ability to play two level four monsters suddenly had the means to deal enormous amounts of damage when the opponent least expected it.
Making their anime debut in 2003, the Valkyrie cards were never printed in the card game until fifteen years later they showed up in the Shadows of Valhalla set. Sadly the unique monsters never saw major success until a different deck found a great deal of use from one of their spells.
Ignoring the Valkyrie specific effects, Goddess Skuld's Oracle allows players to reorder the top of their opponent's deck but they can't normal summon, this suits the Mystic Mine deck just fine since it rarely if ever summons any monsters at all leaving Skuld's Oracle as a powerful deck controlling card.
3. Samsara Lotus
Originally used by the devilish Yubel in Yu-Gi-Oh GX, Samsara Lotus was a bit of a joke thanks to its weird and mostly unhelpful effect.
In the early days of the link era, however, Samsara Lotus became the unexpected core of a powerful combo that could end the game on its first turn by repeatedly destroying and summoning itself on the same turn as Trickstar Black Catbat chipped away at the opponent's life 200 points at a time. Rather than ban the new and immensely popular Trickstar card, Samsara Lotus paid the ultimate price.
2. Grinder Golem
This intimidating looking fiend was first released in 2008 to a lukewarm reception. It seemed to just be a worse version of the famous Lava Golem card. A strong monster that summons itself to the opponent's field and gifts you with a pair of powerless tokens.
It wasn't until link summoning came around that Grinder Golem suddenly began to shine. Since link monsters could use almost any monsters you controlled token or otherwise as material, Grinder Golem stopped being a burden on its owners and started to become free link material.
1. Smoke Grenade Of The Thief
An extreme example, but one that will trigger a fight or flight response in anybody playing the game today. Smoke Grenade Of The Thief was originally released in 2005 and wasn't played in any decks at all. Now though, it's a key piece in the incredibly powerful Infernoble Knight strategy, letting their ace monster Infernoble Knight Emperor Charles tear apart the opponent's hand with ease.
Suddenly becoming a key component in a powerful meta deck fifteen years after it was originally printed isn't just a good example of an old card becoming good, it defines the genre.