Resolution isn't really an "effect". It doesn't really require any specific instructions or hardware blocks.
I never said resolution was an effect. But Gamecube can't output HD, and Zero is HD, therefore by that criteria alone, it couldn't be done on Gamecube.
I agree with you that TEV punched above its weight, and games like Rogue Squadron 2/3, Mario Galaxy 1/2, Jett Rocket, etc, showed that it could produce very nice results. But ultimately it just wouldn't be able to produce the kind of shader usage we see in Starfox Zero. You could downgrade it and replace the shaders with simpler TEV equivalents, but in its current form, the game simply wouldn't be doable on GCN.
Bet with Liquidlaser: I say PS5 and Xbox Series will sell more than 56 million combined by the end of 2023.