Okay, something I have noticed is that the group attacks that are used in the finale of a season are homages to finishers that are used in Super Robot anime series. Now, it is difficult for me to find videos of those attacks from the actual anime series, but luckily for me, there is a video game called Super Robot Wars that should suffice as proof.
The Synchrogazer, for example, was an homage to the Dankukougaken from Super Bestial Machine God Dancougal. So yatte yaruze!
Next up, the Vitalization attack from Symphogear G is an homage to the attack Hell and Heaven from The King of Braves Gaogaigar.
This makes me wonder one thing. What will the Exterminate attack be an homage to? Luckily, I'll be able to find out the answer tomorrow.