I feel fairly certain on most of her specials, but there are a few I just can't fit into anything super concretely.
Neutral B: Heavenly Light
Side B: Angelic Missile, Super Speed
Up B: Jump Glide, Rocket Jump, Warp
Down B: Counter, Reflect Barrier
This leaves: Lightweight, Celestial Fireworks, Autoreticle, and Explosive Flame.
The last side B could be Lightweight, to fit in with the other two being moves that move her quickly horizontally. However, I feel like it might just be possible for Warp to be a side B move and Lightweight her last up B, IF perhaps "lightweight" allows her to jump super high as well as move quickly (similarly to bunny hood)
Celestial Fireworks feels like it's either a neutral B or a down B, but I'd have to say I would lean more towards down B on this one.
Autoreticle and Explosive Flame both feel like they could be either neutral B or side B moves, because they are both horizontally aligned projectiles. I'm going to put them both on neutral B, however.
Tentatively, I'd say her final special moveset would look like:
Neutral: Heavenly Light, Explosive Flame, Autoreticle
Side: Angelic Missile, Super Speed, Lightweight
Up: Rocket Jump, Jump Glide, Warp
Down: Counter, Reflect Barrier, Celestial Fireworks
I feel like Heavenly Light is pretty solidly a neutral special because it's quite simple in terms of it being a raw, large field of no flinch damage, it was the first move they showed in the trailer, and in the image of Kirby with Palutena's hat on, it looks like he is raising her staff in the same way she raises it for Heavenly Light.
As for defaults, I'd say
Neutral: Heavenly Light
Side: Super Speed
Up: Jump Glide
Down: Reflect Barrier