Seiken Densetsu 3/Trials of Mana?
Correct!
1. Choose your heroes, and your villains too
You choose three party members at the beginning of the game, and the one you pick first determines which group of villains rises to power.
2. Justice in name only
As in criminal justice:
Trials of Mana. The word doesn't really have anything to do with the game.
3. Legendary monsters known for their good teeth
The Benevodons. The root words that make up "Benevodon" mean "good" and "tooth". It's weird that they're called this! Some of them don't even have teeth!
4. The important people may vary, but the important rocks and trees are always the same
The mana stones and mana tree have the same role in the story regardless of which route you play.
5. Cameos from the future
Li'l Cactus and Anise were introduced to the series in games made after Seiken Densetsu 3, but appear in the Trials of Mana remake.
6. The character growth system is important to the story, but the choices you make with it are not
Duran's motivation at the beginning of the game is to level up and change his class, and the fourth class changes are a plot point in the remake's postgame, but choosing light or dark classes doesn't affect anything but your appearance and combat abilities.
7. The main characters are all around the same age, but one of them really doesn't seem like it
They're all supposed to be in their late teens, but Charlotte looks and sounds much younger than that.