Definir jQuery Validate mensagens padrão

Adicione isso a um arquivo JS e inclua após o plugin jQuery Validate

jQuery.extend(jQuery.validator.messages, {
required
: "This field is required.",
remote
: "Please fix this field.",
email
: "Please enter a valid email address.",
url
: "Please enter a valid URL.",
date
: "Please enter a valid date.",
dateISO
: "Please enter a valid date (ISO).",
number
: "Please enter a valid number.",
digits
: "Please enter only digits.",
creditcard
: "Please enter a valid credit card number.",
equalTo
: "Please enter the same value again.",
accept
: "Please enter a value with a valid extension.",
maxlength
: jQuery.validator.format("Please enter no more than {0} characters."),
minlength
: jQuery.validator.format("Please enter at least {0} characters."),
rangelength
: jQuery.validator.format("Please enter a value between {0} and {1} characters long."),
range
: jQuery.validator.format("Please enter a value between {0} and {1}."),
max
: jQuery.validator.format("Please enter a value less than or equal to {0}."),
min
: jQuery.validator.format("Please enter a value greater than or equal to {0}.")
});