No offense, but you'll have to rework all of your Pokemon. Their movesets are not good. To tell the truth, I'm surprised that you got that far with those movesets. Also, I'll suggest that you don't look for movesets here, or in another fan-made website. Better seek in the official websites. A good place to search for the best movesets for particular Pokemon and roles is in the official magazines by Nintendo and the Pokemon Company. They're almost completely different than the movesets we see here. Hope I help!
First, Blaziken is fast and can knock out most enemies with single hits, however, he will never be able to outspeed and defeat all Pokemon in one hit so you'll need a move to work up for this weakness, even in-game, especially if the enemy's Pokemon are on much higher levels than your Pokemon.
Good in-game moveset for a level 63 Blaziken:
Usually a Blaziken at level 63 could defeat his Metagross of higher level with one hit from Flare Blitz or Fire Blast, and, if by any chance it survives, it would be by a pinch, so Quick Attack would finish it off. Your choice of Fire type moves on Blaziken are a bit weak to fight Mega Metagross with. Your other Pokemon need to be reworked, but not as much as Blaziken. Usually, any of them could defeat that Metagross pretty easily.
Now, let's discuss why, of this basic moveset
Most players think a powerful move with low accuracy like Fire Blast, Thunder, and Hydro Pump, etc his bad because it miss the target with a chance of 30% to 25%. However, in all magazines they explain that, in the end of the ingame and most of competitive places like Battle Tree and Battle Tower, a standard move with 90 base power will not be enough in most circumstances, so you always have to give it the most powerful move it can learn, especially if your Pokemon is a frail one. The odds of your Pokemon hitting your target with a move like Fire Blast, for example, are still too high and, in most cases, you knock out the opponent Pokemon in one hit. (the best defense is a good offense) However, most foes will endure for example, Flamethrower, so you'll have to use it twice to defeat them. Also, they will endure your 90 base power moves, in most cases, and they will defeat you in one hit, because they are using the most powerful moves they can have. So, even if you hit your 90 base power move, the odds that your Pokemon still get KOd in one hit after scoring a hit is huge. So, in the end, using moves like Fire Blast, Hydro Pump, etc. ensure you more survival, even if you have a slight chance of missing the hit.
So the best fire move for blaziken is Flare Blitz, Fire Bast/overheat based on his overall stats, however in-game what matters most is level, (Not saying that EV is not important, it sure can help a lot) so ingame you can just choose however you like most over the three.
Quick-attack is your backup killing move, even with the best EV in speed your Pokemon will be out speeded a lot, even Mega Blaziken. So sometimes your opponent is in a pinch almost dying, but he always hit your first, and can kill you in the first hit, so using quick attack, Aqua missile, fake-out can ensure you the victory acting first.
Sky Uppercut that is nothing much to tell, is just a good fighting move you can have in level 63, since is the level you are now.
Rock-slide that is also nothing much to tell, is just a good move to have to cover more ground, or itself against some weakness, but almost any other move of any type, besides the same moves you already have, will do good, something like earthquake for example.
Hope with that information you can rework your movesets and defeating them
I aways defeat the elite four second and mos times being underleveled, sometimes having a good moveset works better than having a high level Pokemon, but both are important, and level also is very important in-game. (Make sure your enemie doesn't have at least 15 levels above your strongest Pokemon)
Use this knowledge to choose the best moves for your other Pokemons in their respective levels, also don't bring two Pokemon with mega stones for the elite 4 and champion, bring only one with mega-stone and the other five with standard items.