Yeah, Obito can't put Hulk down. Yes he can obviously hurt him, but not put him down. No one in Naruto contains 1/10 of the strength Hulk has other than possibly the bijjus's and some other creatures. He should be able to literally pass through anything he thrown at him. Also just because that anti-matter attack hurt people like the 4th, 3rd, and other differs doesn't mean it will hurt Hulk. I wouldn't be suprised if Hulk punched out the 10 tails to be honest. The only way I can see Hulk going down is if Obito uses some form of Amaterasu, which is hotter than a sun. If it truly is Hulk will be ashes.
Orion is extremely strong, but a morals off Bill is crazy. If their on an inhabited planet, Bill is going to go all out and bust that ish up in Orion's face. This would be a very good fight but Bill 6/10 times. To make Orion fans feel better, I'll throw in that Orion has a better chance against Bill than the man of steel would.