Unfortunately there is no Sims 3 cheat that maximises all skills...yet.
Chat with our AI personalities
Just use the boolprop cheat in the neighborhood and go to your skills and just click and drag on them.
There are cheats in The Sims 2: Castaway: Max Skills, All Plans, All Relationships, Maximum food and resources. But first, you have to unlock the Cheat Gnome. To unlock the Cheat Gnome: Left Trigger Right Trigger Up X Right Trigger
All though There is the fire code there is no cheat for it
maxmotives
maxmotives is the cheat that instantly puts your Sims in good moods and turns all mood bars green.