Sure! Below is a Python function to generate test cases for the given problem statement.

```python
import random

def tcgen():
    # Generate the value of N
    N = random.randint(1, 18)
    
    # The number of stones is 2^N
    num_stones = 2 ** N
    
    # Generate the hardness values for the stones
    A = [random.randint(1, 10**9) for _ in range(num_stones)]
    
    return N, A

# Example usage
N, A = tcgen()
print(N)
for hardness in A:
    print(hardness)
```

### Explanation:
1. **N** is randomly selected between 1 and 18, inclusive.
2. **num_stones** is calculated as \(2^N\), which gives the number of stones participating in the contest.
3. **A** is a list of integers where each integer represents the hardness of a stone. The hardness is randomly selected between 1 and \(10^9\), inclusive.
4. The function returns \(N\) and the list \(A\).

### Example Output:
Here's an example of what the generated output might look like:

```
3
154315
999999999
472472
354354
832498
9999999
483483
675767
```

You can use this function to generate various test cases for your problem. Each time you run `tcgen()`, it will produce a new set of inputs.