Learn English – Art-related idiom

The most common idiom for something heavy is not a single word. You will hear it commonly when people are trying to lift heavy things:

This weighs a ton!

It's really more of a hyperbole than an idiom, but it is what's said.

A contrarian, perhaps?

a person who takes an opposite or different position or attitude from other people

This in commonly applied in economic contexts, but it is applicable in other cases too.

EDIT: To describe their act of "presenting the same stuff with a new name", you could consider

old wine in a new bottle (uncountable)

An existing concept or institution offered as though it were a new one.

(Wiktionary)