So: Kyon & Kivat - same seiyuu; Momo & Mikuru - they are both from the future; God Gundam & Haruhi - Haruhi is supposedly of divine nature; Metron & Yuki - aliens; (why Metron though?) Ultraman & Godzilla & blue giant - well, they are giants.
But why are there Garren, Taniguchi and Kyonko? I don't see the connection...