Lol well, Predators has many more new elements than P2. We just don't "register" it because the movie didn't really deliver, but the potential was onscreen.
Predator dogs, a different species of predator, a game reserve planet, the falcons, River Ghost, a human using predator technology(and no, picking up a weapon doesn't count, no effort or creativity there), more of a predator teaming up with a human, a predatory doctor that sees himself as one of the creatures. If the movie had a bigger budget and a better cinematographer, and lost the "Ten Little Indians" paradigm, we could've had a really cool, epic scifi film.
P2 has new elements but they're just tastes, they're flavors. Oh they don't kill pregnant woman ok, oh they have a trophy room ok(we knew they collected trophies from P1), oh there's more of them(they're onscreen for a minute and don't do anything) and one gives a human a trophy, oh look new weapons.
P2's biggest mistake was not making Keyes and his team the focus, the main characters. P2's second biggest mistake was making every character's arc be completed by their death. Do we really need everyone dead?! Danny sure, but why kill Lambert or Keyes. Again, too many group killings.