The leader of the Crystal Gems versus Superman. Superman, at his peak, is 6-A to Pearl's 6-B. Let's take a look at their stats.
Attack: Pearl is Country level, with Superman being Multi-Continent level at his peak.
Speed's equalized.
Durability: Pearl is Country level, and can regenerate as long as her gem isn't shattered, retreating into it if her body takes extensive damage. Superman is Multi-Continent level.
Pearl has Weather Manipulation, Sand Manipulation, Size Manipulation, and Light Projection, though I haven't seen those episodes (or much past Season 3), and not sure how they exactly work. I'm also not sure how often Pearl would use Shapeshifting, if at all in combat. But for now, let's assume she can and will use these.
Superman has ice breath, heat vision, flight, and takes his powers thanks to the sun. And his projectiles are probably faster than what Pearl can use, so that gives him an advantage.
In conclusion, I'm not sure if Pearl would stand a chance. Even if Superman doesn't think to destroy the gem the first time, he could probably take down Pearl a 2nd time, due to his stronger attack and durability. For now, I'm voting Superman.