The biggest weight a college gives is to the student's grades, the rigor of their classes, and the student essays. There are problems with the SAT (correlates with income, not success in college) and recommendations (some counselors/teachers are just crappy writers or didn't know the kid that well). While colleges may allow the SAT or recommendations to be submitted, they use it as a datapoint in tie-breakers or for their waitlists. However, I'm hearing more and more that colleges aren't even looking at the SAT score or recommendations. But it certainly depends on the individual college and every one seems to be doing something a little different right now.
The best thing a kid can do if they want to get in their dream school: Push themselves to take rigorous classes (honors, AP, world language, challenging electives) in classes they enjoy and are good at, but don't overschedule/overwhelm themselves. Push that line but don't cross it because it doesn't help to take a bunch of AP's and get D's and F's. The next thing is for students to be involved in extracurriculars and community service where they have an opportunity to put their knowledge and skills to use in real-world situations. They have much stronger applications if they can speak in their essays (and the recommender in their recommendations) to their leadership, supporting their community, skills they learned outside the classroom, their commitment to practice (sports, competitive academic clubs), etc.