Question

Like maybe Normal gem making S-dance 4x. Or does it only apply to attacks

Answer 1

Gems (Japanese: ジュエル Jewel) are
one-use type-enhancing items
introduced in Generation V. There are
17 types of Gems, one corresponding to
each of the 17 types. A Gem is
consumed when the Pokémon holding it
uses a damaging attack that matches
the Gem's type; the attack's power is
boosted by 50%. Gems are usually found
in dust clouds.

-bulbapedia

so in short: NO