This is a pure fun deck, no meta and it is really vulnerable to fire spells. Nothing really to take serious but it can be quite agressive/protective at some points. It's a simple "race"-based evolution/+support effect deck. I'm sure there are better terms to discribe it correctly.
I still missing a lot of OCG cards that i still even don't know yet. Keep this please in mind when making any constructive and polite suggestions for improving this deck.


Light

Light creatures:
2x Supernova Venus La Saint Mother
2x Invincible Giant Mecha Spartan J (comes rarely into play, so it might be exchangable for True Mechaking Thunderbird RE: or Invincible Gomach V)
2x Chief De Baula
3x Rotund Robota
2x Captain Mechagoron (--> could be replaced with Freezing Kachikochin or Miele Thunder Gemwing too)
(+2x Petrova, Channeler of Suns? as protection against single fire removal)

Light spells:
2x Panic Room
2x DNA Spark

Light Fortress:
2x Silver Glory, Invincible Fortress


Water

Water Creatures:
4x Osmosis Bullet Soul Skull Hunter
2x Shuff Eureka
2x Oboro Kagerou, Moonlight Mecha
2x Chivalrous Robo Gentlemen

Water spells:
4x Mecha Machine, Secret Fusion
2x Xanatic X
2x Shadowflash Revival Spiral

Multi

Multcoloured creatures:
2x El Kaiou, Spirit Mecha King
2x Mil Armor, Mecha King Vizier

Multicoloured spells:
1x Miracolous snare

I considered some of these http://duelmasters.wikia.com/wiki/Great_Mecha_King
and looked through all of these cards too:
http://duelmasters.wikia.com/wiki/Category:Great_Mecha_King

Thanks for taking a look!