Does it allow you to force your opponent to attack their own Pokemon?
From what I can find on Smogon, Spotlight allows you to redirect attacks toward an enemy Pokémon:
"At first I was thinking "oh a worse Amoonguss" till I heard the discussion on Spotlight on the Smogon Discord. AFAIK, Spotlight is sorta like Follow Me, except you target an opponent and make all attacks go at it! That sounds brutal if really works like that, and certainly gives it a niche over Amoonguss!"
"It absolutely works that way, complete with +3 priority. It also allows you to target your Ally so that attacks can be redirected to them if you want, which will pair well with Spiky Shield, Baneful Bunker, and Counter/Mirror coat. Shell Trap would also pair well if it didn't also hit all adjacent Mons. Did you know that Shell Trap has 150 BP? Crazy stuff this Gen is bringing."
Bulbapedia also says that it "may affect anyone adjacent to the user."