In Marvel's The Defenders, they mentioned it various times that they used the last of the reviving "life substance" on Black sky, then how was Bakuto revived?
Elektra ( Black Sky) was revived at the end of Daredevil season 2.
Elektra died in "A Cold Day in Hell's Kitchen" (Marvel's Daredevil, S02E13) and her corpse was placed in the "ancient device", but she was never resurrected.
From the episode's synopsis:
Natchios sacrifices herself to save Murdock, and he defeats the rest of the Hand with help of Castle, who looks to move on from his past and accept the Punisher mantle. [...] The Hand later exhume Natchios' body, and place her in the ancient device.
—"Daredevil (season 2)", Wikipedia
In "Worst Behaviour" (Marvel's The Defenders, S01E03), we are treated to a flashback (made clear by a "Months ago" card) at the beginning of the episode, which shows the sequence of Natchios being resurrected.
Months ago, the Hand acquired the ancient weapon Black Sky—the body of Natchios—and used the last of their resources to resurrect her.
—"The Defenders (miniseries)", Wikipedia
The only explanation is that Bakuto's death in "Bar the Big Boss" (Iron Fist, S01E12) happened before the sequence we see in the "Months ago" flashback in "Worst Behaviour", therefore giving the Hand time to resurrect Bakuto.
It's sloppy writing, but plausible, and because we see Bakuto resurrected it means that's what happened.