Evolution Soda does help Mega Evolutions - gives you a cost-free way of searching for them. Of course it can be used for other things as well. I know Mega Evolution does look like more of a temporary forme change in the VGC, but seeing as they specifically use the term 'evolution' (on the Mega Venusaur card as well - 'When a Pokemon EX Mega Evolves . . . '), I guess that's what it is.