Not best practice. This can be done with time O(n) and space O(n) using a dictionary.

This is very slow since it is using two for loops making it at worst O(n^2).

Because brute force O(n^2) is better practice than a hashed O(n) solution

Length property is not calculated.

No need to cache Length of an array;

too many calculations of numbers.Length. better to assigh it's value to a local variable

Only uses Integer and Boolean.

So it was my intention NOT to use any non-integer calls ;)

If no numbers equal "target", it would raise an exception with "index out of bound" on the inner loop.
Not very durable. Maybe that should of been one of the tests?!

I like this. the j = i + 1 is what I like. Reduces the iterations whilst not requiring an identical index check.

You don't need to test the last number in your first loop. You can stop at "numbers.Lenght-1" since the second loop start at +1.

I would not call buble sort best practice.