trainers !
That is the correct spelling of "trainer" (an athletic coach, or animal tamer).
Trainers.
Trainer is a singular noun, meaning one trainer. Trainers is the plural noun, meaning more than one trainer. Trainer as a singular possessive is trainer's with the apostrophe before the s. Trainers as a plural possessive is trainers' with the apostrophe after the s.
The plural way to spell studio is studios.
The plural is hooves.
The plural is cherries.
The plural is cantaloupes.
The plural is resources.
The plural is "emeralds."
The plural is roses.
The plural is bridges.
Trout is plural