So after scanning Ivysaur's move set, I think I have found the moves that are unique.
His Up Tilt is one of few where the hitbox doesn't go up in an ark.
The only other character that has a multi-hitting forward tilt is Wolf, and even then they aren't the same.
Ivysaur's Forward Smash is the only one that returns you to your original position after moving you that far forward. That's using your head Ivysaur! (Get it? cause Ivysaur launches himself headfirst?.....Never mind)
Ivysaur's Up Smash is the only one that is just an explosion. (I know it's spores, but I think explosion sounds more epic.
)
Ivysaur's Down Smash is one of few that comes out on both sides at the same time.
Bullet Seed is unique, but you already knew that.
Vine Whip would be unique because nobody else has a tether that is an Up Special.
I hope this will convince you that Ivysaur is in fact, unique.
As for changes to his moveset, I think the Meteor Smash in his Down Arial should be easier to hit. His Back Arial should deal more damage... ANd that's really all I've got at the moment.