Well, out of the three of them, two of them are Archers. The Caster Gilgamesh isn't even really qualified for his class.

[He's just using stuff he found in his vault. Which is pretty much how Nero became a Caster, too...Archer and Caster are both the joke classes that let everybody in, let's be honest.]

But His Tackiness and his younger self are both Archers.