Log all default Gutenberg Blocks in Console Log

getDefaultGutenbergBlockNames.js

// grab all block types
const types = wp.blocks.getBlockTypes();

// filter to just the core blocks
const core_blocks = types.filter(
    type => type.name.startsWith( 'core/' )
);

// grab just the names
const block_names = core_blocks.map( type => type.name );

// display in the console
console.log( block_names );

Use this while Gutenberg Editor screen is open