He's the 3rd son of a rich family. Spoiled by his father, he's usually making absurd demands for his birthdays: a private soccer court with lights to play the night, 100 volumes of world soccer videos and a school ground exclusively for soccer (Memories 2, part 1, pages 3 to 6).
However, these demands aren't just whims, and he's using these gifts to fulfill his objectives, like being a regular on his school team in 4th grade or winning the national tournament in 5th grade (Memories 2, part 1, page 7).

He looked down on Mikami's achievements when he first met him, but as Mikami admitted, his abilities were proportional to his attitude, as he indeed felt that Wakabayashi could change japanese soccer in the future and that he may become the best goal keeper in the world (Memories 2, part 1, pages 10 to 12).
He also asked for his schoolmates Morisaki, Takasugi, Izawa, Taki and Kisugi to use honorifics when addressing him even if they are the same age, because he was a regular in the team when they weren't. However, this was to motivate them to get better (Memories 2, part 2, pages 13-14). They first were angry at him for acting in such a conceited way, but Morisaki eventually revealed Wakabayashi's true feelings (Memories 2, part 1, pages 25-26).

Mikami is the one who first mentionned to him the idea of becoming a "S.G.G.K.", a "Super Great Goal Keeper" (Memories 2, part 1, page 21).

He has pride in his abilities and recognize the abilities of his schoolmates, he won't hesitate to scold someone and grab him by the collar if he's implying that him or his schoolmates are starters just because his father has influence on the soccer club (Memories 2, part 2, pages 9 to 14).
After Mikami helped him realize his objective of winning the national tournament when he was ony in 5th grade, he said that Mikami would become the best GK coach in the world once he wins the World cup (Memories 2, part 2, page 28). Conjecture: It may show that they grew closer compared to the first time they met. End of conjecture.

Morisaki, Takasugi, Izawa, Taki and Kisugi kept on using honorifics, and said it was because they grew accustomed to it (Memories 2, part 2, page 29), Conjecture: But it may also be because they have a lot of respect for him because he stood up to them. End of conjecture.