I'm not sure if this belongs here but I couldn't find a "Superflat Worlds" section. So I'm posting it here.
3;1*minecraft:bedrock,53*minecraft:stone,1*minecraft:lava,4*minecraft:tnt,4*minecraft:dirt,1*minecraft:grass;1;village(size=3 distance=28),mineshaft(chance=0.03),stronghold(chance=28 count=15 spread=2),biome_1(distance=32),dungeon,decoration,lake
That's the superflat code. You have grass with 4 more layers of dirt then 4 layers of TNT. After that, a layer of lava and below that is 53 stone. Finally, there's 1 layer of bedrock. I also added that all natural structures are more common plus villages are larger.
! WARNING ! Use with 2GB+ of RAM. My MC almost crashed with 3GB - it was running at 2FPS. Actually not too bad.
! NOTE ! Build up VERY high. I set my base as the top of one of the churches in a village and I got obliterated.
Hope you have fun with this!