The flower gun is the most expensive and consequentially the best in the tier that you've classed it in. Yet stats don't dictate actual performance. You say that the stats create a rift between the flower gun and the other guns in it's tier. How then do I (and I'm sure you too) witness other guns classed in that tier beat the flower gun in a fair matched battle? The flower gun gives more for it's price. But it's far from over-powered.

On the other hand, note the watermelon and apple launchers are just that...launchers. They are meant to hit heavy punches with a slow firing rate. Speeding them up would defeat their purpose and theme. People often make the mistake of spamming their guns, rather than taking the right shots at the right time. These two launchers could easily crush other guns if used by players correctly.

At the end of the day, the guns are more or less appropriate. And it comes down to how players use them. If you're armed with one of the launchers and expect to spam you're way through a fight, then you're not using your weapon properly and to their full potential. It would be a no-brainer that you'd be destroyed. But if you know your game and your weapon, everyone is fair.