Kuriboh is definitely one of Yugi Moto's most famous monsters. While lacking in the stat department, the monster has an ability that's spared the duelist's life points time and time again. The harmless-looking Kuriboh is surprisingly useful enough that there have been numerous variations of the card, spanning most of the Yu-Gi-Oh! franchise. However, Kuriboh's got a little something special that transcends its trading card nature.
Namely, it seems like Kuriboh has some level of sentience. Aside from expressing emotion and affection in a way that few other monsters can or do, Kurioboh also has an unsanctioned extra ability. In the Virtual World arc, during a duel against one of the Big 5, Yami Yugi has to pick a Deckmaster to fight alongside him. While he considers which monster he wants and thinks about the Dark Magician, Kuriboh acts on its own. Coming out of the virtual card and showing the Pharaoh some affection, the monster is revealed to have chosen itself as the Deckmaster. While one could argue that, since it's in a virtual world, this could be an anomaly in the program, but it doesn't negate the fact that Kuriboh demonstrates more autonomy then the rest of the world's virtual monsters.
But Yugi's not the only one: a good number of protagonists across the franchise have also had some game-breaking experiences with the Kuriboh family. The most notable is Jaden Yuki and his Winged Kuriboh. Yugi gave Jaden the card in a chance encounter, but it turned out to be something more meaningful than a printed piece of paper. Winged Kuriboh was actually a rare card housing a Duel Spirit — a living, sentient (if ephemeral) creature Jaden could personally interact with, though few others could see it. This Duel Spirit freely moved with Jaden as a companion and partner, but was also known to place itself on top of Jaden's deck whenever he needed it most, especially in the manga. This would then allow Jaden to take advantage of its card ability — usually in a deck built for the inclusion of a Winged Kuriboh — to win the day. However, this isn't exactly surprising, as Yu-Gi-Oh!'s heroes are well known for their skill at cheating. Regardless, the bond shared between Jaden and his living Kuriboh is very similar to that of Yugi and his possibly-living Kuriboh.
While it's clear that Winged Kuriboh often affected Jaden's game, whether Yugi's own Kuriboh did the same is a little less so. While it's definitely a stretch to say that Kuriboh influenced every card he drew, if it does have sentience then it could easily influence where it stands in the deck, taking chance out of the equation. With that, Kuriboh could stall long enough for Yugi to pull off another strategy, which it often did. But whether that was its own choice or Yugi's luck of the draw is up in the air. However, if Kuriboh is truly sentient and can influence when it appears in its owner's hands, then this is yet another cheating tactic perfectly tailored to protagonist types. Eat your heart out, Kaiba.