Monster Hunter style 1-2 shot

[Railak]

So I've had this idea of doing a sort of Monster Hunter style thing. Not actually the game of it, but the hunting giant powerful monsters thing. It would turn it into a game with the party competing against other groups to bring down bigger badder monsters. Each monster would be ranked on a scale of points. Usually the more dangerous the more points, but also rarity will be a thing. And the monsters aren't just bog standard creatures. I don't want to make up monster stats, so templates and things to make monsters more powerful, also thinking mostly beast level intelligence
So the party would be all level 15, cause this is a prestigious type world hunt only for the elite hunters of the world.
D&D 3.5, Pathfinder, and all published resources within those categories are allowed, specially for making the monsters.

I need monster ideas, so far I have;
Thunder Rex, a half blue dragon T-rex (both Pathfinder versions, there might be more to it, I don't exactly remember, the stats are in a notebook that is at another location)

I'm not stuck, I just started, and I figured that some people might find it fun to make some monsters. And I'm looking for ideas that would create unique challenges as well, and not just obliterate the party.

[Maat Mons]

I've got a good one.

You start with a dog. Not a wolf or a riding dog. Just a dog.

Size: Small
HP: 6 (1d8+2)
AC: 13 (+1 Dex, +1 natural, +1 size)
Attack: Bite +2 (1d4+1)
Abilities: Str 13, Dex 13, Con 15, Int 2, Wis 12, Cha 6
CR: 1/3

Then you add the Titanic Creature template from MM2.

Size: Gargantuan
HP: 362 (25d8+250)
AC: 26 (+0 Dex, +20 natural, -4 size)
Attack: Bite +30 (3d8+24)
Abilities: Str 43, Dex 10, Con 31, Int 2, Wis 12, Cha 6
CR: 13

And finally, you add the Young template from Pathfinder.

Size: Huge
HD: 312 (25d8+200)
AC: 25 (+0 Dex, +18 natural, -3 size)
Attack: Bite +29 (2d8+21)
Abilities: Str 39, Dex 14, Con 27, Int 2, Wis 12, Cha 6
CR: 12

Yeah, it's only CR 12. And it doesn't even deserve a CR that high. Since any 15th-level character should just be able to fly overhead and attack this land-bound enemy with impunity.

But the point of this encounter isn't to challenge the players. The point is to make them realize that they're the real monsters. And make no mistake. Anyone who kills a huge puppy is a monster.

Make sure the rules of the contest only give them points for killing things. Not just for subduing them in non-fatal ways. And have an NPC who is clearly Cruella de Vil offering a large cash prize for the creature's pelt. But maybe also have a second NPC offering to make them awesome puppy-skin armor if they bring the pelt to him instead.

If you do things right, they might be so preoccupied deciding which reward they want to collect for their puppy-murder, that they never even stop to think if maybe murdering a puppy is a bad thing to do.

[Railak]

Lol I like your thinking xD

And to add insult to injury I'll make its fur red xD