I think BK/WK will have the moves upon capture. Almost every "big legend" comes with their signature moves when caught unless they either don't have one (Weather trio), or didn't have one at the time (Mewtwo). Also note that various media compares IB/FS as being stronger than R/Zs Fusion attacks, as opposed to BF/BS. The Ice attacks are getting advertized pre-release like the Fusion attacks, where's BF/BS were not. BF/BS were basically "rewards" for getting R/Z to Lv100.
It's possible that the Kyurems get the respective Fusion attack at Lv100, but it wouldn't be as fitting since the Fusion attacks are about R/Z hitting each other to boost the other one's attack. WK is resistant to Electric, but BK takes neutral from Fire, ruining the balance. Since IB/FS are being compared to the Fusion attacks in marketing, as well as canonically being corrupted versions of BF/BS, I don't see Kyurem getting any of R/Z's signature moves.
I can see Kyurem getting the level up moveset of R/Z based on the respective form, allowing access to the Fire and Electric attacks. I wouldn't be surprised if the TM compatibility remained the same however though.
Interesting to note, a trailer for M15 depicts Kyurem to be using Flamethrower. Normal Kyurem could get access to multiple Fire and Electric attacks. Don't be surprised if turning into Black Kyurem removes any Fire moves, and vise versa however. GF clearly does not want Reshiram using Electric attacks, and Zekrom using Fire attacks (HP doesn't count in this regard), so the same might follow with BK and WK.
If BK/WK get IB/FS upon capture, and they don't get any of R/Z's moves, what would become of their Lv100 attack? Could there be some kind of unlock that either removes the charge up turns of IB/FS, or grants invulnerably like Shadow Force? Perhaps an item, say the God Stone, can be obtained after getting to Lv100 that does those respective things (or perhaps act the same way as the DPPt trio's orbs, maybe even both)? Or GF could just troll us and give us nothing.
Judging from theeir stats in the screen shot, assuming no EVs, they probably have the following BSTs:
HP does not change between formes. Kyu's had 130 in Atk stats, R/Z had 150 in their higher one. 170 seems logical. R/Z had 120 in the lower Atk stat; 125 makes sense (fits well with 125 HP). Defenses seem low; so 100 and 90 are reasonable. Speed is probably going to drop, since GF never lets the original forme be completely inferior, not to mention R/Z only had 90.
Even if Black and White Kyurem miss out on movepool and removal of charge up, a Draco Meteor and Outrage coming off of what appears to be 170 in their offensive attacks is nothing to laugh at.
Even if BK/WK might fall short in terms of moveset