Required Fields will never have a default value, empty defaults means null.

All Fields can be set via setName e.g. block.setUnlocalizedName("name"); and gotten via getName;

Name	Type	Required	Default Value	Notes
Name axisAlignedBB	Type MCAxisAlignedBB	Required No	Default Value Full Block	Notes Lets you set the block's bounding box
Name beaconBase	Type boolean	Required No	Default Value false	Notes Can this block be used as part of a beacon's base?
Name blockColorSupplier	Type IBlockColorSupplier	Required No	Default Value -1 as color	Notes The block's color
Name blockHardness	Type float	Required No	Default Value 5.0	Notes How long it takes to break
Name blockLayer	Type String	Required No	Default Value "SOLID"	Notes "SOLID", "CUTOUT_MIPPED", "CUTOUT", "TRANSLUCENT"
Name blockMaterial	Type IMaterialDefinition	Required No	Default Value Iron	Notes The Block's base material
Name blockResistance	Type float	Required No	Default Value 5.0	Notes Explosion resistance
Name blockSoundType	Type SoundType	Required No	Default Value Metal	Notes The Block's sound type (determines things like the breaking sound)
Name creativeTab	Type CreativeTab	Required No	Default Value Misc	Notes The Creative tab the item will appear in
Name dropHandler	Type IBlockDropHandler	Required No	Default Value ​	Notes What the block will drop when broken
Name entitySpawnable	Type boolean	Required No	Default Value true	Notes Can be used to prevent any entities from spawning on this block
Name enumBlockRenderType	Type String	Required No	Default Value "MODEL"	Notes "INVISIBLE", "LIQUID", "ENTITYBLOCK_ANIMATED", "MODEL" → Sets how the block is rendered
Name fullBlock	Type boolean	Required No	Default Value True	Notes Used for rendering and light calculations
Name gravity	Type boolean	Required No	Default Value false	Notes Is this block affected by gravity
Name itemColorSupplier	Type IItemColorSupplier	Required No	Default Value -1 as color	Notes The block's color when it is in item form
Name lightOpacity	Type int	Required No	Default Value 255 if fullBlock is true or 0	Notes Does Light pass through
Name lightValue	Type int	Required No	Default Value 0	Notes Light level of block, ranges from 0-1. This value is multiplied by 15 to determine the final value.
Name onBlockBreak	Type IBlockAction	Required No	Default Value ​	Notes Called when Block is broken.
Name onBlockPlace	Type IBlockAction	Required No	Default Value ​	Notes Called when Block is placed.
Name onRandomTick	Type IBlockAction	Required No	Default Value ​	Notes Called on a random tick event.
Name onUpdateTick	Type IBlockAction	Required No	Default Value ​	Notes Called when Block receives a block update.
Name passable	Type boolean	Required No	Default Value Depending on the IMaterialDefinition provided	Notes Can players pass through this block?
Name replaceable	Type boolean	Required No	Default Value Depending on the IMaterialDefinition provided	Notes Can this block be replaced by another block?
Name slipperiness	Type float	Required No	Default Value 0.6f	Notes Ice blocks are 0.98f
Name textureLocation	Type CTResourceLocation	Required No	Default Value null	Notes The block's resource location, used for textures etc.
Name toolClass	Type String	Required No	Default Value pickaxe	Notes Tool required to Break Block
Name toolLevel	Type int	Required No	Default Value 2	Notes Tool Level required to Break Block
Name translucent	Type boolean	Required No	Default Value false	Notes Is see through
Name unlocalizedName	Type String	Required Yes	Default Value ​	Notes Name, should be all lowercase
Name witherProof	Type boolean	Required No	Default Value false	Notes Can Wither's destroy this block

ZenScript
 Copy
#loader contenttweaker

import mods.contenttweaker.VanillaFactory;
import mods.contenttweaker.Block;

var antiIceBlock = VanillaFactory.createBlock("anti_ice", <blockmaterial:ice>);
antiIceBlock.setLightOpacity(3);
antiIceBlock.setLightValue(0);
antiIceBlock.setBlockHardness(5.0);
antiIceBlock.setBlockResistance(5.0);
antiIceBlock.setToolClass("pickaxe");
antiIceBlock.setToolLevel(0);
antiIceBlock.setBlockSoundType(<soundtype:snow>);
antiIceBlock.setSlipperiness(0.3);
antiIceBlock.register();

You will need to add tile.contenttweaker.blockName.name=Localized Name to the responding language files.
If you have doubts, take a look at the display name of the item when you're holding it before translating it.

Alternatively, you could use CraftTweaker's localization feature, though it's recommended using the language files!