Remember how characters like Meta Knight or Lucario looked slightly "fuzzy" around the edges during their victory screens? That is gone. The HD packs sharpen the character textures dramatically. You can actually see the stitching on Captain Falcon’s suit and the individual scales on Charizard’s back.
Battle portraits and character icons (CSPs) are often redrawn or upscaled for better clarity.
Even the 2D elements get love. The character select screen, the CSS (Character Select Screen) portraits, and the battle UI are upscaled to look sharp without losing that specific Brawl "paper-cutout" aesthetic.