>>52428641Mewtwo, at least on the main line, is a lot more animalistic/robotic(?) than cell.
He just... builds a next and waits for strong Pokémon to fight with. Makes you wonder if you choose the cave close to Cerulean because it is filled with strong wild Pokémon or if they are attracted by Mewtwo somehow. I fill like if Mewtwo was like cell it would go around challenging champions/e4, as its sole desire is fighting.
As for groundon and kyo... isn't their conflict literally them fighting over territory?
Deoxys is a Mythical so he is a weird spot. We haven't seen him do anything in games, sure he was inside the meteor in ORAS but nothing seems to indicate it is anything but an animal. All dex entry focus on how it is mutated virus.
As for Necro, it is in a strange place, it clearly has a goal (becoming complete again) but is it just following its instinct to survive or does it have a goal?
I think a better example of legendaries with human like behaviour are the genies, who are just... fucking around for self amusement. Landorous acting like father keeping the other 2 in check.
Of course all of this when talking about their behaviors on the main line games. Spin-offs and the anime are their own canon.