Is my elite four team good?

its a great team all around. in terms of items you should give elektross nothing so that acrobatic's power is doubled you have it, samurott maybe a mystic water, simisear nothing as well for acrobatic's power, haxorus should delete dragon pulse for swords dance. It would be pretty useful to swords dance then use false swipe once to bring reshiram/zekrom to 1 HP. As for Unfeazant im not sure, you could go with tailwind to help your team move faster, or aerial ace in case the elite four decides to mess with accuracy.