Second place intelligence will realize it's advantageous to stay dumb. They'll be smart enough to choose to become weak.
The first species to reach planetary control will cause a greater inequality between the other species. Posing a threat to a competitive civilization will cause their extinction, like a virus paralyzed by medicine. Covid is facing annihilation as we actively sniff out any vulnerablity to exploit.
Therefore, a second species to reach an intelligence sufficient to pose a threat by its mere existence will suffer genocide. Their best shot for propagation is staying dumb, helpless and silent. Planetary dominance is a zero sum game. It's why churches, countries, parties compete.