# [Brain-Flak], <s>474</s> 470 bytes

    (((()()()()()){}){}){({}<(()()())>[((((()))))])}{}{({}<>)<>({}<>)<>({}()<>)<>}<>{}{}{([({}[()])]{(({}[()]))<{(<{}>)(((((((((()()()()){}){}){}()){})[(()()()()){}]){}())(()()){}())){({}<>)<>}}{}({}[()]){{}<>(((((((((()()()){}()){}()){}){}()){}))[((()()()()){}){}()])[(((()()()()){}){}()){}()])(<>)}>}{}()){({}[](<>))(<>[()])((()()()()()){}){(({}<({}())>)){({}[()])<>}{}}{}<>([{}()]{}((((()()()){}){}){}){}<>)<>{({}((((()()()){}){}){}){}<>)(<>)}}{}<>((()()()()()){})<>}<>{}

[Try it online!][TIO-jfxt6snn]

[Brain-Flak]: https://github.com/Flakheads/BrainHack
[TIO-jfxt6snn]: https://tio.run/##dVFBDgMhCPwOHPoDQ9J3EA/bXto06aFXwtstIBp3N4tGcYAZ1Mdve39f2/PTGpjhGCgaE0RLwkgMkeNWUUUjSlho2QHDs7NEBhvGYPlVYLhYBIooIUw7yGp3eQ3UDkMevY/ZgJrWYBfHDsyDcSj03fn3yl7PcEYzBCampB1xveqIw6F8ekCI54t0ygrPK06h0SYHsS1rq3PG3bzsMhwdad54J55/0Fq73f8 "Brain-Flak (BrainHack) – Try It Online"

Gosh, it's nice to finally check this off my to-do list.

###Explanation:

Brain-Flak is obviously not very good at getting the modulo of numbers, so I bypassed this by pushing all the elements first.

    (((()()()()()){}){}) Push 20
    { Loop 20 times
    	({}
	    <(()()())>    Push a 3 to represent a Buzz
	    [((((()))))] Push 4 1s
        ) And decrement loop counter
    }{} Pop the excess 0
    { Loop over the list of numbers
    	({}<>)<>({}<>)<> Transfer two of the elements to the other stack
    	({}()<>)<>       And add one to the last one
    }<>{}{} Pop the excess two elements

Now `1` represents normal numbers, `2` representa `Buzz`, `3`s represents `FizzBuzz`. Initially I just pushed the values that repeat every 15 numbers 7 times and popped the excess 5, but this way turned to be slightly shorter.

    { Loop over each element
        ([({}[()])] Subtract one from the current element
        { Fizz and/or Buzz
            (({}[()])) Subtract 1 again
            <
            { Push Buzz
                (<{}>)(((((((((()()()()){}){}){}()){})[(()()()()){}]){}())(()()){}())){({}<>)<>}
            }{}
            ({}[()]) Subtract 1 again
            { Push Fizz
                {}<>(((((((((()()()){}()){}()){}){}()){}))[((()()()()){}){}()])[(((()()()()){}){}()){}()])(<>)
            }
            >
        }{}()) Push 1 if it's a number
        {
            ({}[](<>)) Push length of list to other stack
            (<>[()])((()()()()()){}) Push -1 and 10
            Div/mod algorithm
            {(({}<({}())>)){({}[()])<>}{}}{}<>([{}()]{}((((()()()){}){}){}){}<>)<>
            Pushes n%10+48 to output stack and n/10 to the list stack
            { If div is not 0
                ({}((((()()()){}){}){}){}<>) Add 48 to it and push it to other stack
                (<>) Push 0
            }
        }{} Pop excess 0
        <>((()()()()()){})<> Push newline to other stack
    }<>{} Pop extra newline
</code></pre>