Heres the final calc: -6 0- Atk Slow Start burned Chansey Frustration vs. +6 252 HP / 252+ Def Shuckle through Reflect: 0-0 (0 - 0%) -- aim for the horn next time
(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)
(Chansey's Level 1 and Frustration has 1 base power.