To the Max Achievement
To the Max40
Level up any Skylander to level 15
The maximum level any Skylander can reach in Skylanders Giants is level 15. To reach it, play with the Skylander of your choice as much as possible, and only switch out when you need to. If you do this, you should get to 15 by the end of the game.
If you have a level 10 Skylander you used in Spyro's Adventure, this will be that much easier, as the Skylander will continue leveling from that point. Be sure to take ownership of the Skylander in this game.