What the fuck is a grand Zamboa?
I dunno I had to use wiki
Gurando Janboa) is the mecha piloted by the Anti-Spirals' avatar. After the Great Gurren Brigade formed the Tengen Toppa Gurren-Lagann, the Anti-Spiral created a similar machine to battle it, containing the Anti-Spiral homeworld in its forehead "gem". Its styling is similar to the Tengen Toppa Gurren-Lagann, for the sake of defeating the Brigade at its own game, thus showing the galaxy the ultimate failure of their greatest warrior yet; sowing despair and draining Spiral Beings of their power.
Grand Zamboa is Anti-Spral's mech. I assume that's what you're asking.
I remember hearing "Zamboa" is supposed to be some moon (non-JP) word for "totem" like a totem pole. Grand Zamboa was based off of TTGL so I'm not surprised it would have a face name as well.