It all depends on the colour palette and values as a whole. There's practically no limitations on what colour a particular object is as long as everything else supports it. Variation in the tones gives you tools to create different time of days and seasons for the same material, you can look at different areas for example in Zelda games and notice the grass can be teal, bright warm green or even brown depending on what atmosphere they wanted to create.
That teal grass is quite extreme in comparison to everything else in the pokemon picture which creates the nice contrast and redability, but I can see why some people would prefer a more limited palette (like let's say Link to the Past, which had way less contrast in the green fields). Similar bright teal grass can be found in Minish Cap also, but there the overall colour balance is better in my opinion.
