Let's break down what you might be looking for:
* "Happy birthday batch" - This phrase is grammatically correct but might be used in a specific context. It could refer to a group of people celebrating birthdays together, like a "birthday batch" for a company or a class.
* "Grammar" - This refers to the rules of a language, which in this case might mean you're seeking a grammatically correct way to wish someone a happy birthday.
If you're looking for a grammatically correct way to wish someone a happy birthday, here are some options:
* "Happy birthday!" - This is the most common and straightforward way.
* "Wishing you a very happy birthday!" - This adds a bit more emphasis.
* "Happy birthday to you!" - This is a more formal and traditional way.
If you have another phrase or specific context in mind, please provide more details, and I'll be happy to help you with the grammar.