Construct a validator with a list of rules the same size of your input.

for($i = 0; $i <= count(porcentaje); $i++){

  $rules['porcentaje.' . $i] = 'required|numeric|between:0,100';

}

$validator = Validator::make($porcentaje, $rules);

Not sure if I understand the question correctly.

To show custom message, http://laravel.com/docs/validation#custom-error-messages

$customMessages = array(
   'customer_name.required' => 'Hey, you forgot to put your name! '
);

$rules = array(
   'customer_name' => 'required'
);

$validation = Validator::make($data, $rules, $customMessages);

// If your html input is an array, hence <input type="text" name="customer[name]" />,
// you will do this. 

$rules = array(
    'customer.name' => 'required',
);

$customMessages = array(
    'customer.name.required' => 'Hey you forgot to put in your name !!',
);

$validation = Validator::make($data, $rules, $customMessages); 

To add custom message for each of you fields its the same thing :

for($i = 0; $i <= count(porcentaje); $i++){

  $rules['porcentaje.' . $i] = 'required|numeric|between:0,100';
  $messages['porcentaje.' . $i] = 'porcentaje invalid';

}

$validator = Validator::make($porcentaje, $rules, $messages);