I found a vegan sponge cake recipe, but it's totally different than regular sponge cake and really didn't sound so good.
I went and googled that out of curiosity.
Traditional egg heavy sponge cake - 16 egg yolks, sugar, water, flour, baking powder, salt, vanilla, lemon extract.
Vegan sponge cake - sweetened soy milk, cider vinegar, flour, cornstarch, baking powder, baking soda, sugar, vegetable oil, vanilla extract.
The only ingredients they have in common are flour, sugar, baking powder and vanilla extract, which are in a significant fraction of baked desserts, while the method for preparation vary so much that the only common factor is that it is baked.