Movie Casts:

Ran : Koyanagi Yuu
Nao : Hanada Tatsuomi
Princess Emerana Lourdes Esmeralda : Tsuchiya Tao
Ran & Nao's father : Ishibashi Tamotsu (He is Wakura Eisuke, the captain of the Night Raiders in Ultraman Nexus)
Ran & Nao's Mother : Sato Yasue (She is Saijyo Nagi, the leader of the Night Raiders in Ultraman Nexus)
Space Pirate members : Hiraizumi Sei, Kitarou & Bengaru
Ultraman Zero : Miyano Mamoru = Gundam 00's Setsuna
Ultraman : Kurobe Susumu (Hayata)
Ultra Seven : Moritsugu Kohji (Dan)
Mirror Knight voiced by Midorikawa Hikaru = Gundam W's Heero
Glen Fire voiced by Seki Tomokazu = G Gundam's Domon
Jumbot voiced by Kamiya Hiroshi = Gundam 00's Tieira

Well, both actually... Nexus is 'Noa' (Next) who is a protector\guardian of space and time (He is the Light). The Visitor encounter Noa before, a long time ago. Noa protected them from the invasion\attack of Space Beasts, probably for quite a long time... ~ Speculation: In the same time, Noa probably protected other world as well, which included Earth. He is the Guardian after all.

After that, the Visitor try to create their own 'Light' which turned out to be a disaster when it became corrupted and turn into Darkness (The One aka Dark Zagi). The Darkness somehow became the master of Space Beasts (of course, it is said that these are the manisfestation of dark emotion - fear, grudge and ect), and he promptly destroyed the Visitor's planet. The surviving Visitor thus fled (abandoning their original form to hide themselves), and finally find themselves on Earth.

Noa arrived too late of course and engaged in a violent\awesome\titanic battle with the Darkness (aftering the Visitor) through out the galaxy or universe, which lead both of them (both seriously hurt and depleted) to Earth which lead to the event in Ultraman The Next.

And the rest is history. ~ This is partially referenced from the movie, the tv series and some article.

Yeah, my favourites are Nexus, Gaia and Tiga as well... Ultraseven X was a more traditional episodic SF style, so the focus on the main plot was never heavy enough until the last few episodes.

Well, it will be more along the line of Noa, the Guardian of Space and Time and supposely Protector of the Light (Ultraman). The people of Baraj were workshipper of Noa, back in one of the original Ultraman episode... Nao's pendant is supposed to originate from fragments of the Shield of Baraj. Might be related...? 

Well, to be honest, I have yet to watch the original series, but according to the episode summary, it was during episode 7 when a statue of Noah (a statue of ultraman) was found in a middle eastern town called Baraj, this is the episode where Antlar first appeared. Oh yeah, the title for episode 11 of Ultraman Max was called, "Prophercy of Baraj" where Antlar appeared as well...
So, yeah, Baraj and Noah or Noa... You get the idea.

Ultimate Zero!

Maybe Zero should wear this type of armours:-
   

I don't hate Project DMM, but neither do I like them, they are just - okay. Voyager is a bit soft in their execution though, their voice is not strong or high spirit enough.