Generally, when you level up in the Pokewalker, you don't see your stat gains.
If your Charizard gained ten Speed EVs, than eventually the game would calculate it to boost Speed since it doesn't always distribute it right away.
When you level up in the Pokewalker, it IS indeed like a Rare Candy level up, or a Daycare level up where you just gain a level rather than EVs. Keep in mind, the game will not give you your EVs right away, so If you see no difference or anything, don't fret.
Sorry if I didn't answer your question, it was a little hard to understand it, but I hope I did. ~