Another newbie here, but I tried to do some research.
To outspeed that Typhlosion you'll need 215+ speed, which means either you go with Quick Claw (which its unobtainable by then) or get another pokemon to do so.
Your fastest pokemon (base stat wise) should be Hawlucha. It can outspeed, but I doubt you can one hit that Typhlosion.
The other option is Houndoom. It's your second fastest pokemon, and Flash Fire is a huge bonus, since that Eruption will do nothing. Try to get the speed up to 204 to outspeed the Darmanitan (since Rock Slide).
You should be able to get a chunk out of its HP if you land Inferno, though I'd try to get more accurate special moves instead of gambling on a likely to miss one.
From Toxicroak onwards, none of them is fast enough.
Field-wise, Rain. Rain will get rid of most of her strategy (Fire-move spam) and you can use it to your benefit. I'd try to use this at the beginning after Eruption (since it wont work on an overheated field) and when Ninetails comes out (since Drought is a problem). Not only that, you can Surf-spam your way through as long as your partner resists it. You can also use Blizzard when the field is overheated, but you have to land it.
I'd seriously consider that Lycanroc though, if possible Midday form.
If you want a speedy one, with 22+ IVs, EV trained and a Speed bonus nature (this last one is the important one) it'll be faster than any of her pokemons.
Not only that but, the attack it has combined with a rock move should do quite a lot of damage, maybe even sweep.
Hope it helped and good luck with it :D
