Did anyone see the summary Pokébeach has?
This has some differences from PPK's translation
By this translation it seems like the prize is a cup... which means as expected this isn't an official Contest with a ribbon as the prize
And also by this translation it seems like Ash/Brock and than May/Dawn battle the owner of the restaurant and not each other
May, who is attending the "Wallace Cup" contest, meets up with Ash's group and takes them to the popular Seven Stars Restaurant. However, when they get to the restaurant they are told that the Pokemon Battle-loving owner won't serve them unless they beat her in a Tag batle. So, Ash and Brock, then May and Dawn, challenge her to a match!
This has some differences from PPK's translation
By this translation it seems like the prize is a cup... which means as expected this isn't an official Contest with a ribbon as the prize
And also by this translation it seems like Ash/Brock and than May/Dawn battle the owner of the restaurant and not each other