Gamecube: Sonic Adventure, does it require a memory card?

You need a memory card to save your game.

So does it require one? No. But unless you want to restart your game everytime you play, you'll need to invest in a memory card.

The Gamecube does NOT have any internal storage & the Wii disables internal storage when you run a Gamecube game...

So you'll need a Memory Card if you want to save your progress. There's no way around it!

Game Cube doesn't has internal memory.

You need to buy a memory card unless you want to restart the game every time you turn the console off.