Can Talon fourth-wall your character at all?: Sure!
Action/prose fourth-walling?: For your narration, sure, that's fine! Probably wanna ask for comments on my narration, though; Pinkie's a pretty open book, but there might be instances she'd need to keep something to herself, like if she Pinkie Promised to keep a secret. (Not that she has much of a poker face, anyway.)
Character fourth-walling?: Oh, definitely! Equestria's a weird place, and Pinkie's one random pony.