Eren YeagervsNaruto Uzumaki

Eren's Founding Titan is one of the most visually terrifying forms in anime — a skeletal colossus hundreds of meters tall leading an army of Wall Titans that systematically flatten civilization. With full Founding Titan powers, Eren can control all Subjects of Ymir, summon previous Titan shifters, and his Rumbling threatened to destroy the entire world. In Attack on Titan's universe, Founding Eren is a world-ending threat.

But Naruto's universe operates at a completely different power tier. Six Paths Sage Mode Naruto dodged light-speed attacks from Madara, created Rasenshurikens that wiped out forest-sized areas with ease, and fought Kaguya — a being who could create and destroy entire dimensions. Naruto's speed alone makes this nearly impossible for Eren. Even in his colossal Founding form, Eren's attacks are relatively slow — Wall Titans walk at a marching pace. Naruto moves at speeds that make lightning look slow.

Eren's army of Wall Titans is his greatest asset, but Naruto can create thousands of shadow clones, each capable of forming Rasenshurikens. A single Tailed Beast Bomb from Kurama devastated mountain ranges — the Wall Titans, while enormous, are still made of Titan flesh that has defined durability limits. Naruto could systematically destroy the Rumbling army while Eren himself would be vulnerable to a direct attack from a Six Paths enhanced Naruto.

The Founding Titan's size is actually a disadvantage here. It's a massive target that Naruto's ranged attacks can hit easily, while Eren has no way to catch someone moving at relativistic speeds.