Species is deterministic: two parents always make the same child (a hidden breeding-power average, plus ~250 fixed "unique combos" like Relaxaurus + Sparkit β Relaxaurus Lux). So the route above is exact.
Passives are RNG. A child pulls from the combined pool of both parents' passives β inheriting 1/2/3/4 of them at roughly 40/30/20/10%, then random junk can fill empty slots. You can't guarantee a 4-passive set in one egg (~10% even from clean parents). The move: use "clean" parents that together hold only the passives you want, breed a bunch of eggs, and keep the cleanest offspring. This tool shows you which passives you already have to work with.
Prototype notes: routes are species-level (they don't yet account for needing one male + one female, or multiple copies) and the breeding data is community-extracted, so a few special Pals may read as "unreachable" until the combo table is fully validated.