Grizzly bear: A 500 pound murder monster with no remorse and even less shits to give, if you are unlucky enough to come across this not-so-nice yogi bear early on in the game, he can and will take you off the census without batting an eye, if you see this fella roaming around, avoid or use a long scope rifle with express rounds to kill him. Also, if you see one standing up, he probably isnt looking for a hug, he is most likely thinking that you look pretty damned tasty.
Black bear: I would give this guy a hug if he didn't run so damned fast, you are more likely to die to a boar than to this re-coloured winnie-the-pooh, though that isn't hard because if you try to step to a boar, he will murk you if you arent concentrating. Unless you are on RDO and playing the "a bitter means to a bitter end" mission, if so this oversized teddy bear will have no problems connecting you to god's Wifi. As for killing the black bear, i have no idea why you would want to unless you care more about a saddle and some cool clothing than this cute bastard, if thats you then use the same equipment as you would for the grizzly, just with more remorse after you pull the trigger cause this boy is just too damned cute.
Legendary Bharati Grizzly Bear: There's a reason our boy Hosea was scared as shit when this furry motherf*cker showed his face, if you do choose to hunt this guy right after you meet him for the first time, good luck, and would you like white or black flowers at your funeral?