Nah it was done on purpose to highlight a story point.

Yuya fused with Yuto, Yugo, and Yuri to become some goblin shit.

Yami fused with Dark Magician in Capsule Monsters 

Joey fused with a suit of armor

Jaden fused with Yubel

Yusei broke his limits, became a super saiyan, and used power of his friends to beat the villain 

Yuma fused with Astral and became a super saiyan (he cheated like crazy whenever he did)

(I haven’t seen anything past Zexal, but I’m sure the newer series didsome DBZ type shit.) 



 




Man this Episode of Super was the Best