agreeing with eggbert in that you either need to run speed on that thing to outspeed tenta or run a cleric on the same team as kyu-b, otherwise if that thing takes a single scald burn or toxic it's essentially useless. pretty amazing though that it only takes 75% max from sheer force lando's focus blast and then ohkos back with ice beam. i'm glad you showed the public this set, ojama, because i feel that for too long people have been utilizing kyurem-b as a completely offensive threat and have ignored its staggering 125 / 100 / 90 defenses, plus its access to dragon tail and roost. the only problem i have with this set is kyurem-b's questionable typing. i understand this particular set is fantastic against rain since kyu-b resists water and its sub won't even be broken by keldeo's rain-boosted surf, but it seems like against a sand offense team, for example, it'll be mostly dead weight. i suppose it could surprise landorus or lando-t with ice beam, or maybe catch terrakion trying to set up on it and phaze it out, but beyond that...i dunno. seems like good team partners would be your everyday rain balance team, i.e. politoed, tentacruel, ferrothorn, jirachi. i'd like to hear what you use, ojama, as support for your kyurem-b set.
some calcs indicate that kyurem-b is still doing about 185% damage to landorus even with a careful nature, so yeah, consider doing that.