HEY UNDERTALE YELLOW SPOILERS HERE. I MODDED THE GAME A BIT
I downloaded the Undertale Mod Tool and this is the result. Ignore the player character I forgot to change that oops
Anyway here's a silly video about one fox's plight in the world of modern politics
(I played the game for roughly five hours straight without bringing up the fact that I knew how to mod it in any capacity for two friends in order to play a silly prank on them. 100% worth it)
A few days ago, I beat Undertale Yellow pacifist route. It was honestly way more emotional than the original game but I had a bit of trouble with the battle system. It almost gets Undertale in its essence. Go play it if you haven’t already!
Here's how I feel Martlet actually saving Clover but falling off the ledge (like your post) would go:
They would end up in the Swampouts from the True Genocide fangame, the inhabitants of which either don't respect or aren't aware of the royal guard so they'd still try to attack Clover, similar to the Steamworks robots when Ceroba is with you
Flowey would give you the friendliness pellets inbetween Clover waking up and Martlet waking up (so Martlet doesn't see Flowey), to give you a chance at beating Undyne, who would inevitably fight Clover after Clover and Martlet find their way to and through Waterfall (temmie armor would be unavailable due to the tem shopkeeper not having intrest in cool leg yet)
Upon waking up, Flowey would also probably say something like "Geez, don't you have brain damage or something? That's the fourth fall you've had at this point!"
Killing any monsters would result in Martlet immediately leaving you, making the Undyne fight unwinnable without killing her
That's all I have for ideas towards your hypothetical
I literally just made that Martlet post thing because I found the idea of Martlet holding Clover, not realizing she needs her wings to fly, was funny. I wasn't thinking of an entire AU around the concept.
Mostly my thought process would either be the game over screen or Martlet realizes that she needs to use her wings and spreads them out, hoping that Clover had now grabbed on.
Do you ever think about Frisk wearing that hat during the fight that gets broadcast all throughout the Underground? Because I've been thinking about it a lot.