He has... a few? Sonic Chick and Quillbolt Hedgehog come to mind, though I wouldn't call those mascots. His signature cards are all of the "cool" variety though, being Stardust Dragon and its various forms, plus Junk Warrior.
It just sucks because Ruka had Kuribon, but in the end, neither Ruka nor Kuribon were terribly important to the plot. Ruka did one or two awesome things during the Dark Signer arc, and then did literally nothing else worth noting for the entire rest of the series. Instead, she was employed as the damsel-in-distress on multiple occasions for Rua to get some character development at her expense.
YEAH, I MAD. I liked the twins, dammit, but hell if the writers didn't ultimately end up favoring Rua over Ruka. D: