Osiris will require copious luck with this deck. Fire Queen shouldn't be that hard, but you need to time Bone Wall and Rain of Fire together for maximum effect. Those Otyughs will make a much, MUCH bigger difference when upgraded.
Expect a fair amount of losses against FGs. They're designed so that no one deck can take them all. I used this deck for a while, and here's a run-down of my experience with each FG:
Chaos Lord - He mutates his own stuff, meaning you have to rely on a lot of luck. Not too hard sometimes.
Dark Matter - Black Holes will shut you down fast and keep you there until dead.
Decay - Pray he gets a slow draw. One Rain of Fire can't kill Pests, and he keeps Fractaling, so it'll require a full field with Bonds or an early boosted Bone Wall and he gets Eclipse late. Even then, super-Siphons can still get you.
Destiny - Fate Eggs once again mean luck, though you can play Permanents without fear. Not too hard.
Divine Glory - Very tough. You need a great draw and a lot of stalling until you have your field set up.
Dream Catcher - Butterfly Effect usually comes early and kills all your Hourglasses and shields. Very difficult.
Elidnis - Very doable, unless he quints a few spirits early. Even then, Bone Wall could hold them off down the road.
Eternal Phoenix - Notoriously difficult, and maybe impossible with this deck.
Ferox - One of the easiest, play all your permanents and creatures without fear, and wait to use Rain of Fire until he's got a good number of small stuff out.
Fire Queen - You need a good start. At least she doesn't Explode things.
Gemini - Can only lobotomize creatures, if she doesn't have a weapon out you don't need to quint your Oty. Neat trick - a single gravity tower is a great target for Steal, it shuts down half the deck.
Graviton - I've not yet succeeded, very tough fight.
Hermes - He comes at you hard and fast, and even Bone Wall won't stop his Fire Lance from finishing you.
Incarnate - Not much of a threat if you play smart. Steal his Graveyards as soon as you can.
Miracle - He can't destroy anything you play. If you can survive his Dragons long enough to set up, you're golden.
Morte - Possible but far from easy. If he gets Arsenic out you need to block or steal it fast, and hope you can get enough healing set up to counter the poison.
Neptune - Usually a breeze, the main threat is his dragons. Permafrost Shield can also stall your Oty and let him whittle at your Bone Wall, but I've only had trouble a couple times.
Obliterator - I've never beaten him, and it would be very rare with this deck.
Octane - Gee, a reflective shield would be such a help here. I guess it might be possible, you would need to play only pillars to draw out his explosions before laying down any hourglasses. He has 4, I think.
Osiris - Nearly impossible to stem the tide of Scarabs once it gets going. I almost made it once, a Permafrost Shield would really, really help.
Paradox - The worst he can do to you is copy your creatures. If you get set up reasonably quickly, this impostor isn't hard at all.
Rainbow - Extremely unpredictable and dangerous, and can do almost anything. I did manage to kill him once, but it was very close, right down to the wire.
Scorpio - Poisons you even faster than Morte, and is harder to shut down. An amazing draw would be necessary to pump healing fast enough.
Seism - Your pillars die right away, crippling you beyond repair. This guy really requires a pillarless deck.
Your most reliable kills will be Chaos Lord, Destiny, Elidnis, Ferox, Fire Queen, Incarnate, Miracle, Neptune, and Paradox. Hope that helps!