I actually have a sim I'm working on to be the ultimate sim. Up until city living and beyond, she has every skill maxed, every aspiration complete, and every trait available. I haven't played her since city living came out, so I now have more to do with her, but I'll get to it eventually. I've also been working on maxing all careers, but that's slower going.
I'm also doing something similar, but far more complex, in sims 3. Look up llandros ultimate sim challenge. He has a series on his youtube, a post here on the forums, and a blog of the rules.
But, yeah, you have to be careful downloading sims from the gallery. All skills, aspirations, and traits transfer.