I think your team lacks against Ghost types. You have two moves against it, one from a psychic pokemon. As it not STAB and most of Ghost mons have good Sp. Def, the first turn will be hit (because of Alakazam great speed) but it is most likely to be taken out on the next turn, because of its weakness to Ghost. Shadow Claw may work fine for Blaziken with Bulk Up set, but I'll get into it.
Now some personal preferences:
Blaziken would be better with Adamant (highest offensive possible) because it will gain speed through Speed Boost, and it usually outspeed most of its foes. I don't like Flare Blitz because of recoil. I woudl go with High Jump Kick and Blaze Kick, than change Expert Belt for Wide Lens, so it will never miss any of those moves. I would also change Shadow Claw for Thunder Punch. Gives coverage and I think it'll work better than Shadow Claw.
I can't tell much about Amoonguss. I don't like Slow mons, it compensates with bulkiness, but lacks in fire power, and I'm all about power. I would suggest Roserade, same typing, fast and stronger. The problem is that it won't have a lot of reliable options to Spore and Clear Smog, only Toxic Spikes. If you like it, keep it, I wouldn't know how to use it myself. I like the idea of Breelom too.
I wouldn't use Alomomola, I just don't like it. I can argue about design and Speed. I also like the idea of Vaporeon, same speed, but way more powerful. Both, I think that lack in versatile movepool. I would go with Starmie Psychic, Scald and Power Gem, you could also use Recover with the same intention as Wish. Slowking would be nice too, still bulkier but with best movepool. Other good options would be Kingdra, Gyarados, Azumarill and Empoleon.
Garchomp. Pseudolegendary, not much to tell. I have a question though: does Devastating Drake with Dragonium Z + Outrage leaves the mon confused?
Metagross. Another Pseudolegendary. I would change it's Thunder Punch for STAB Zen Headbutt + Wide Lens and you'd never miss it and Meteor Mash.
Now, all suggestions I made was to take Alakazam out of your team. Alakazam is a great mon, but lacks in movepool, as you have already stated. Thunder Punch goes to Blaziken, so you can change it on Metagross. Using Zen Headbut on Metagross, makes Gyarados, Azumarill and Empoleon more atractive to the team. After all that, I'd suggest using a Dark Pokemon. You'll have something more solid against Ghost and Psychic. Also something with double typing just to have more coverage on your team. I'd suggest Weavile, Alolan Muk, Drapion or Pangoro.
Also, as LBP2 suggested, try to use something with Earthquake while Garchomp can't learn it. Along with his suggestions, I'd say Krookodile. Using this one, you can keep Alakazam on your team (because of Dark typing) although I think it will be outclassed easily. If with Krooko, A-Ninetales and Gardevoir would be of better use on the team.
I always try to build a team that is strong against every single Type. I tried to not change it too much. Keep in mind that all my suggestions are based on my preferences for pokemon. You may note that all of them have great Attack and Speed stats. It's the way I like to play. I hope it helps. Good luck