I've always loved SMBZ but the thing that breaks it for me is the heroes' stupidity.
Since episode 7, they possess four of the seven Chaos Emeralds. They've bested a Metallix that had used them to turn into a demi-god.
At this point, they should have used the Chaos Emeralds to turn into demi-gods themselves. They would have killed Metallix. They would have found the rest of the Chaos Emeralds. They would have beaten Bowser, Eggman and Basilix easily.
A story where you search for all the Chaos Emeralds is over by the time half of them are acquired, unless the enemy is stronger than demi-gods (inherently or using other power-ups). If the heroes had been smarter, the series should have been over at episode 7 or 8.
That would be anticlimatic, sure. We wouldn’t have seen the heroes use the Star Spirits to turn into godly beings that overcome Super Metallix. But it’s that or the saga gets stupid and unecessarily long.
The same applies for all SMBZ rip-offs that use the same system of collecting artefacts that turn you into a god.
Speaking of anticlimatic, I think I can see the plot post-episode 8 from afar. After all at 9 yo I did think that Mario would be saved either by Shadow or by Luigi (not DK or all the side characters that people came up with).
The main cast bests Metal Mario, Eggman and Bowser. They take Bowser and Eggman's secret Chaos Emerald.
Shadow gets beaten by Metallix, who uses him as blackmail to force the heroes into giving up their 6 Chaos Emeralds (Metallix having found the 7th).
Metallix attacks but the heroes are able to flee. This gives time for the heroes to find help with the Star Spirits. Shadow is angry that they saved him in exchange of the emeralds, but also ashamed to be the reason Metallix will win, not to mention that saving Peach was the right idea as she is the one calling the Star Spirits to help or advising the heroes to search for them. The Star Spirits intervene knowing Metallix will destroy the universe if they stay passive.
At the darkest hour, as the world is burning, the heroes transform into gods and beat Metallix (and maybe Luigi would be noted for being the person that tips the scales in the heroes' favor... maybe thanks to his weird luck, his bravery, his brotherly bond with Mario, or his electrical powers that represent a robot's weakness). Peace is restored to the world, Sonic and Shadow's friends are avenged, and possibly the Chaos Emeralds are destroyed.
Sonic and Shadow could make a trip to Mobius to restore their world, bury their friends properly, let nature take over again. Then they would go back to Mario's world to live there.
In the end, their would be a tiny epilogue scene where a new enemy assembles the Axem Rangers' remains as well as Metallix' to create a new super enemy, and wasn’t there a hint that Mr.L would make an apparition? because Luigi has enough of his poor popularity? Whatever next saga that Alvin Earthworm had hinted at, something I read in a Fandom Wiki page long ago.
Knowing what happens next depends on whether he continues animation or not. If he does, let’s see if my predictions were accurate.
