I've just beaten the elite four, and so far, I've only battled Wally 2 times.
Chat with our AI personalities
It is in Verdanturf.
You can battle Wally a second time after defeating the Pokemon League.
once you have helped him catch a ralts he will be at the end of victory road
After you get the Balance Badge (Norman) talk to Wally's dad and he will give you surf
wally's parents live near your father's gym (wallace, normal type) in petalburg city. there's a sing wich says "wally's house"