>>53271418legitimate answer, the anime is the only media in which a pokemon character has ever smouldered.
It's a modern slang term for peering or smirking at a girl who you like/you are aware would fall for you.
It's a face that (supposedly) communicates that you are on top of the social situation. In most media it's a romantic trope where one character is tripping over themselves while the other finds it amusing. I don't know the trope name