Pianos.
The spelling of the plural noun, enrollees, is correct.
That is the correct spelling of "trainer" (an athletic coach, or animal tamer).
The correct spelling of the plural noun is nostrils(nasal openings).
That is the correct spelling of the noun "colonist" (a settler, plural colonists).
That is the correct spelling of the plural noun "tenants" (renters, residents).
That is the correct spelling of the plural noun fifths.
That is the correct spelling of "dingo" (Australian wild dog).
No, "memorys" is not a plural noun. The correct plural form of "memory" is "memories."
That is the correct spelling of "firefighter" (fireman).
The correct spelling for the plural noun of "screech" is "screeches".
That is the correct spelling of the plural noun "altercations" (fights).
That is the correct spelling of the plural noun "necessities" (things generally required).