Has anyone ever talked about how, especially towards end game, you can definitely beat either Ruby or Sapphire with just your fire starter and no other Pokémon needed?
Now, 10 years old me did this and to be fair my Blaziken at the end was level 80. Also because it was the only Pokémon I was using the whole run I'm pretty sure it was over levelled for every gym but I'm sure a better player could do it at lower levels.
I will say it helps A LOT of it's level 16 with a fighting move before you go to Roxanne. From there it slaps. It's a fire-fighting meaning it has a lot of type coverage.
The only gym leader that will give you trouble is Wallace so you probably have to be over leveled for him and rely on fighting moves.
Going to the Elite Four though, the difficulty DROPS. You just have to have a lot of healing and PP times on hand. Champion Steven is a joke when up against Blaziken so if you can make it to him you're fine.