19.
Wally's ralts evolves into a Gardevoir in RSE, but in Oras it becomes a Gallade and a mega Gallade at that. I always thought this Pokemon line was a good a choice for Wally's signature Pokemon because they are Pokemon that start off small, frail and shy, but they have a rich intuitive life and can with a nurturing trainer evolve into something special and strong, and this Pokemon could even look a little like Wally with the green colors. I think switching the final form to Gallade made it an even closer match to Wally because Gallade is always male, it was also a a good way to show off it's new mega form.