* Triton: 2,707 km in diameter

* Ganymede: 5,268 km in diameter

* Titan: 5,149 km in diameter

* Mercury: 4,880 km in diameter

* Pluto: 2,377 km in diameter

Here's the breakdown:

* Ganymede and Titan are larger than Mercury and Pluto. Both Ganymede and Titan are significantly larger than Mercury and even dwarf Pluto.

* Triton is larger than Pluto but smaller than Mercury. Triton is a little bigger than Pluto, but considerably smaller than Mercury.

So, the answer to your question is:

* Yes, Ganymede and Titan are larger than Mercury and Pluto.

* No, Triton is larger than Pluto but smaller than Mercury.