Remember, diabellstar can kick his ass since he has only 1800 atk, even if he uses his link 1 equip for a bonus, he's still only at 2400, compared to her 2500 atk, and diabellstar has about a half dozen or more spell/traps she can search to further kill him if he revives, which she can also do. Tldr: she's stronger than him in every regard except as a splashable engine in the meta as it stands.