Is it advisable to take trivial classes to better focus on independent study?
I assume that you are talking about applying to graduate programs in mathematics, rather than in other disciplines. 

To take remedial courses so that you can focus on "graduate level theory" on your own seems like a spectacularly bad idea. Why would a grad school take someone whose transcript shows remedial courses instead of accomplishments in upper-level undergraduate and graduate coursework? It also weakens your overall transcript in the process, since the remedial course will stick out like a sore thumb. Moreover, without some mechanism for documenting the work that you've done on your own, you won't easily be able to convince an admissions committee that you've actually done the work!

If you want to do graduate-level work, just take the graduate-level courses corresponding to what you want to do.