We could probably see Poke-Jurassic Park in Akala Island in Ultra
How do you think it'll work?

We could see tons of other Pokemon there not limited to fossils like Golisopod, Rhydon, Relicanth, Aggron, Sharpedo,Tyranitar, etc.
It could work like a Safari Zone or an Island Trial where you find a bunch of smaller pokemon before finding the fossil mon