Almost every rental application in the GTA asks for the same short list. If you assemble it once, properly, you can apply to a dozen units without scrambling each time.
What to prepare
Completed rental application: most landlords and brokerages use the standard OREA Form 410. Fill it in fully; blanks read as evasions even when they aren't.
Photo ID: driver's licence or passport for every adult who will be on the lease.
Proof of income: two or three recent pay stubs, or a letter from your employer on letterhead stating your role, salary, and start date.
Credit report: your own, pulled recently. Equifax and Borrowell both let you do this without affecting your score.
References: a previous landlord and one personal or professional reference, each with a phone number that gets answered.
Bank statements: usually only asked for if your income is irregular, but worth having ready.
Ontario's Human Rights Code limits what a landlord may consider. Refusing you because of your family status, ethnic origin, age, disability, receipt of public assistance, or because you have children is prohibited. A landlord may ask about income, credit history, and references, but the Ontario Human Rights Commission's guidance is that income information cannot be used on its own to screen you out.
You are also not required to provide a Social Insurance Number. Many applications ask; you can decline and offer your own credit report instead.
A note on the rental application form
I hand clients a fillable copy of the standard rental application so they can complete it once and reuse it. That document isn't hosted here yet.