The Whac-A-Mole game from Episode 40, the Dream Card episode. Sakura was struggling to hit all the moles coming from all around her, so Meilin decided to grab a hammer and help her out. With each other's backs covered, they had the time of their lives smashing up moles. Especially awesome is that Meilin used to hate Sakura with a passion and constantly distrust her when they first met, but at that moment, they were playing together like they've been best friends forever.
Against the Twin Card, Syaoran and Meilin's perfectly synchronized attack was the greatest display of Badass Normal in the whole series.
The second greatest being Meiling vs the Fight Card.
Except that the Windy wasn't transformed at that time, it just had reinforcement from the Moon Bell. The Firey was the first card to be transformed.
Also, how Sakura caught The Jump. Specially because at some point the girl (who mind you, was still a Na´ve Newcomer and basically realising how the deal worked) summons The Fly while taking a huge fall and being upside down. A little mistake and she would've died, but she managed to get this perfectly done.
With the risk of applauding assault against a minor, The entire Final Judgment. Poor animation aside it was one of the most brutally actioned scenes in the anime.
A meta example: NISAmerica managed to rescue it. They're giving it the full blu-ray remastered treatment. Best of all, they're using the Animax dub, which, according to Madman Entertainment, is supposedly EXTREMELY taxing and hard to get (even though it's in mono only). That takes massive balls and guts to do. They must really love this show if they managed to give it this much royal treatment.