Yugi and Kaiba's rivalry is one of the most intense in anime history. Surprisingly, Yugi has achieved something in Yu-Gi-Oh! that Kaiba has not and may never be able to attain due to his own actions. Interestingly, this accomplishment seems to be more fitting for Yugi.
The Dark Magician, belonging to Yugi, and the Blue-Eyes White Dragon, belonging to Kaiba, are just as iconic as the two duelists themselves. These extremely rare and powerful cards give Yugi and Kaiba an advantage over other duelists in the anime. It is worth noting that Kaiba acquired the only three copies of the Blue-Eyes White Dragon in the world, having won the fourth from Yugi's Grandfather and subsequently destroying it. Alongside these iconic cards, both Yugi and Kaiba possess other well-known cards such as Kaiba's Obelisk the Tormentor and Yugi's Exodia and Slifer the Sky Dragon. However, in each case, Yugi has achieved what Kaiba was unable to.
Yugi Has Beaten His Own Yu-Gi-Oh! Monsters While Kaiba Hasn't
The Battle City Arc showcased an extensive tournament where Rare Hunters, duelists who wielded powerful and scarce cards, were abundant. Throughout the competition, Yugi encountered opponents who utilized each of his most iconic cards. Initially, Yugi triumphed over Seeker, who employed multiple copies of Exodia, the card responsible for Yugi's first victory over Kaiba. Subsequently, Yugi faced off against Arkana, who employed a variant of the Dark Magician. Additionally, Yugi confronted Duelist Strings, an opponent who initially possessed Slifer the Sky Dragon before Yugi successfully claimed it as one of his own defining cards. Consequently, Yugi emerged victorious against duelists utilizing his iconic cards, a feat Kaiba failed to accomplish.
Considering the rarity of the Blue-Eyes White Dragon, Kaiba never encountered a formidable opponent who utilized his own strategic approach. Although he tested an AI he designed that employed three Blue-Eyes White Dragon cards, this pales in comparison to battling against a real person. The opportunity may have arisen during his duel against Yugi's grandfather, but the aged man's weakness undermined the significance of the victory. During his encounter with Pegasus in the Duelist Kingdom, Pegasus managed to pilfer Kaiba's Blue-Eyes White Dragon and transform it into a Toon Blue-Eyes White Dragon. However, Kaiba was unable to secure a win in that particular game. Hence, Kaiba has yet to conquer his own monsters in the same manner as Yugi.
If Kaiba were to ever discover this, it would undoubtedly infuriate him, considering the intense rivalry he shares with Yugi. However, it is logical that Yugi would have this achievement while Kaiba does not, as Yugi is recognized as the King of Games and therefore capable of triumphing over any strategy, even his own. Consequently, although Kaiba may boast numerous remarkable dueling feats in the world of Yu-Gi-Oh!, he will never possess the capability to surpass Yugi's ability to conquer his own cards and strategies.