Learn Turkish: Yetenekli olanları bulmak lazım. - It is necessary to find the talented ones.

This is a perfect example of omitting the noun after the -an suffix. It comes from the verb olmak (to be) plus the subject relative suffix -an, making olan ("the one who is"). We add the plural -lar to get "the ones who are", and then the accusative suffix -ı. Together with yetenekli, it means "those who are talented" or "the talented ones".

Could we just say yeteneklileri instead of yetenekli olanları?

Yes, you can! Yeteneklileri bulmak lazım also means "It is necessary to find the talented ones." However, grouping people by using an adjective with olanlar (literally "those who are [adjective]") is a very common and natural pattern in Turkish.

Why does olanları have an -ı at the very end?

That -ı is the accusative case suffix. In this sentence, "the talented ones" is the specific direct object of the action bulmak (to find). Because we are talking about finding specific people, we must use the accusative case on the object.

Why is the verb bulmak in its dictionary (infinitive) form here?