I recently saw boys going to shul on scooters and skateboards is that a problem
For a young child it would be considered a toy, however for older children and adults it should not be done because it is uvdin d’chol (weekday like, and not the type of thing we do on Shabbos).
Piskei Teshuvos 248 ftnt. 33, Orchos Shabbos 19-ftnt. 95, Nishmas Shabbos 6-281, R’ Y. Berkowitz Shlit”a, Poskim.