I don't know if that would work, because I can't see anyone who's become friends witht he gang turning on them.
Well, there is one that might.
As for villains, I also like the leaf eater villain, though personally I thought Rinkus and Sierra were leaf eaters and maintain it as all Sharpeeth have been seen trying to make a go at the kids or, if they don't, are obviously Sharpteeth.
While Sierra has, it's likely because of hatred of Ducky rather than trying to eat her.
As for the villain that is like Prince Hans, I like that idea. As for knocking a hole in the Great Wall, like that idea too. As for Rinkus and Sierra returning, like that too.
As for intelligent villain, like that too.
I have long focused on the idea of an omnivore villain. One that I'll give teeth but that nobody would know he had sharp teeth. He would plot to rule the entire world and the Great Valley and also perhaps a Sharptooth valley would be his last places he didn't control or have minions controlling by the time of the Land Before Time finale.
Also, for dark effect, he'd have helped Sharptooth, though we didn't know it, get to Mama Longneck and hence have a role in the death of Littlefoot's mother.
My villain though, often wouldn't be seen killing directly, other than perhaps some random birds. (Though he will turn out to have given Red Claw his good looks, showing he's a danger to Sharpteeth and Flatteeth alike.) He might attack and show his true colors and kill Leaf Eaters and maybe a Sharptooth or two in a big battle near the end. Ultimately, I had the villain be tail whipped by Littlefoot, who was fighting to save both himself and Ali,, and the villain would fall into lava in the Mountains that Burn.
He would be someone who thrives on racism so that he can divide both Leaf Eater herds and Sharptooth packs so that they never merge with others and he knows that they are as strong as they are untied and as weak as they are divided.
He'd also have four other minions of his own type, in addition to Red Claw, Screech, Thud (who ultimately joins Chomper and turns on the villain and Red Claw), Rinkus, Sierra, Ozzy, and Strut (who also goes rogue and joins Chomper).
As for who we'd sacrifice, I'd say the Old One. She'd be really near the end of her life anyway by the time the Gang of Five are about of age and also her death, especially the villain would set Chomper's girlfriend and the Old One up so they ended up fighting and Chomper was forced to intervene and the Old One got fatally wounded and Chomper nearly gave into his instincts, and is chased out of the Great Valley, with even Littlefoot turning on him eventually. Ali is mad at Littlefoot for what happened with the Old One, who turns out to be her great-great aunt or something, and Ali and Littlefoot's relationship nearly tanks.
Then, as Littlefoot kinda hindered the others from getting Chomper, Topps and others demand Littlefoot be banished for life, and Grandpa Longneck very painfully agrees (don't worry, Littlefoot and Chomper will eventually be pardoned for everything.)
After Littlefoot is gone, the villain starts criticizing the leadership, and, as he appears pretty wise, they give him more and more power.
He, meanwhile, starts inflaming racism everywhere in the Great Valley, though doing it so subtly that it appears the herds are doing it and not him and soon there are high tensions, which the villain "resolves", appearing to be more and more of a great "leader".
Conveniently for the villain, everyone blames Chomper for all the crimes he's actually committing.
My other villain ideas was a Sharp Beak who married a Pteranodon and had a son but eventually she feared her mate would leave her and take her son with her, so she'd lure him away and eat him and tell her son that his dad with a Sharp Beak too and was murdered by Leaf Eaters, making her son hate Leaf Eaters. Fearing that her son might find out he's half leaf eater, she'd keep him always under her eye and never let him go far. Eventually though, he'd give her the slip, and, after some misadventures, end up in the Great Valley.
She'd not be a direct threat to the Gang of Five till her son met the Gang of Five, eventually befriended them, and later seemed to like them. She'd threaten to harm the Gang of Five as blackmail to make her son come back and she'd even try and kill them all, her own son included, when the truth came out. (She'd get knocked out and fall into a tar pit and die. Always wanted to see a LBT villain die in a tar pit.)
Also, I had an idea where Topp's father would come back, be really racist, and make a big mess. Also, Topps and his father would have some threehorn and a one horn enemy and they'd want to fight them to prove they are tough.
Also, I had the idea for bad young leaf eaters that would get Littlefoot to try and get some underground stone that would supposedly give knowledge and this would enable a trip under the Great Valley for a change. (We could have a sharptooth mammal in this one too. Perhaps a Smilodon.) These leaf eater villains, anyway, would get Littlefoot to start being mean to his friends. His friends would suspect what is going on, but Littlefoot, feeling unappreciated by the grown ups, would desire this object and even break his friendship with the other members of the Gang of Five at one point. Eventually, Littlefoot would realize what is going on, try and back out, the others would kidnapp one or more members of the Gang of Five to try and make him comply, and well, I still am working on what would happen then. I'd like to have a longneck villain in this one if I could.
