Starting with Question 2.
Question 2: What technology?
Godzilla DAM and STE were the big winners. Make the game exactly like those, but with updated visuals. It was the perfect system for Kaiju fighting. G:Us was awkward, floaty, overly simple, and just all around odd and poorly optimized with little thought put into characters movesets. You should basically just import the movesets of all the monsters you can from STE to the new game. Not being able to roll, and the horrible jumping in G:U made fighting a terrible chore.
One interesting option, with your art style, would to cell-shade the characters. Go for a whole "manga" inspired aesthetic with the UI and menus, as well.
Question 1: Which set of monsters?
A full scale licensed Godzilla Game would be preferable, as Gamera offers too little a roster. A custom Monster set would be cool though. What would be the BEST, is if you combined the Godzilla roster with the key players in Gamera, and added a couple unique creations.
If you're limited to just Godzilla, however, Keep ALL the monsters in the roster for G:U, but add:
Godzilla 70's(Think kickboxer-based moveset with spammable beam weapon ala Baragon's in STE)
Sanda and Gaira(Alternate costumes of the same monster, add easter-egg Frankenstein costume?)
Biollante should be demoted to a non-playable boss monster, as I don't think she works well as a playable fighter.
Perhaps add more Boss monsters, like Dogora, or Gotengo(Not the badly implemented one from G:U, though).
If you add Gamera monsters, the possiblities increase greatly. You have Gamera, Iris, Zigra; and Legion would make a cool boss monster.
If you could also create some kind of Ape-like stand in for both Kong and a mecha counter part, that would be awesome, as it would be impossible for Pipeworks to get the rights to the official versionsAs for monsters I left out, they would work great if implemented as "assist trophies", like how Super X and Battra appeared in STE. These monsters are weaker and can only really do one thing.
Dimension Tide(That'd be the scary one)
Question 3: What platform?
Consoles, easily. Not even a question. Put it on a console with a controller suited for fighting games
, like 360 or PS3. or whichever one of them comes next.
OTHER FUN STUFF:
is a MUST. Its' not enough that you just have online, but also what you can do with it. Please give players options regarding military attack intensity, frequency of power-up drops, which power ups drop, what music plays, destructability of buildings, even gravity.
Bring back RAGE attacks! Critical Mass was lame...
Also ensure a decent amount of online modes, such as Basic Versus, Melee, Tag Team, Destruction, and Mini-games. The mini games from STE were pretty cool.
Let us record matches and watch the replays!
Also, a half-baked city builder would be awesome for custom arenas!
Make achievements/ Trophies references to kaiju films!
Alternate costumes for monsters would be cool as well, but make them hard to unlock. Make unlocking monsters themselves, really easy so it isn't a bitch to accumulate a roster before taking it to a friend's house.
Also, bring back Day/Night options for cities!
Make maps more STE esque, not G:U esque. They were easier to get around and fight in. Also, bring back the boxing ring!
I also can't stress enough, that if you put Gamera into a Godzilla game, Pipeworks would be considered a God among the fanbase and a boundary breaker. So many precedents would be set. You guys should find out if there's any way you could do that.
AND FOR THE LOVE OF GOD PLEASE BRING BACK THE OLD NARRATOR!