Engine + both electric motors with of course basing it off of 75% of the electric motor numbers due to efficiency.
That's not how it works. Toyota engineers will be fired if they design a hybrid system with 75% efficiency.
In all hybrid vehicles the power is not determined by engine+motor, it's engine+battery. The motor is not an energy source, the battery is.
Toyota rates THS power in two different ways:
On 'regular' hybrids, the rating is power at the output shaft of the hybrid transmission. The power is slightly lower than ICE+battery power.
On LC/LS500h the rating is simply ICE+battery power without accounting for losses in PCU, motor, and planetary gear set. They do this to 'inflate' the rating for 'performance' reasons.
In both cases the motors are oversized for engineering margins. The only exception is the 1.8L system on the Prius/Corolla hybrid where MG2 is undersized (for maximum efficiency) so total output is limited by MG2 not battery.