She's as good as a Pokemon character can be in my opinion, which isn't saying too much what whit the likes of Ash Ketchum being the most well known human and possibly the most jarring.
Pokemon, for the longest time has not pushed any boundaries with the main series of games; the ideas of friendship and growing stronger with your Pokemon can only go so far and Zinnia brought just that but with a storyline twist (if you can call her lineage that).
Now, you're probably thinking I'm just hating on her character at this point but I assure you that isn't the case.
Here's a comparison, N from B/W was a both a thought provoking character and blatant love interest, let's be real concerning that ferris wheel scene... He questioned the philosophy that as children, we strives to achieve for; wanting to be the very best like no one ever was, catching them all like a test, scavenger hunt, or just a challenge we issue to friends but N made it clear that something about that was messed up. Capturing Pokemon against their will and forcing them to battle, albeit there will always be that person who argues that Pokemon love to fight which I like to debunk by using the first Pokemon movie as ammunition.
IN ANY CASE, the fact remains that N was the closest thing to being a genuinely "good" character, even despite me not liking him too much.
Zinnia however, again, is just a good "Pokemon" character which doesn't mean much when characters like Kratos from Tales of Symphonia, MegaMan X from the same titicular series, and even N from the SAME SERIES exist.
Let me repeat myself, she isn't bad; just not all that special either.