As you already have 5 badges, I’ll assume that you can obtain any TM in game except Psychic. I’ll also assume that you can also breed many moves.
Blaziken:
Timid nature means fast special attacker. In Pokemon Insurgence, Blaziken has poor selection of special moves. To perform better, you may need to change the nature into Adamant or Jolly.
Flame Charge is redundant in Blaziken if you can obtain one with Speed Boost. Protect, Wildfire, or Hone Claws can be used instead.
If you want to build critical specialized Blaziken, equip it Scope Lens and have Focus Energy on its moveset. After one turn of Focus Energy, Blaze Kick and Slash will always crit.
DGardevoir:
Best nature in your team, according to me
Ice Beam and Frost Breath are redundant. Go for Nuzzle, Thunder Wave, or Livewire instead. Nuzzle is used to paralyze opposing Pokemon while damaging it, but if catching Pokemon is your real test, use Thunder Wave instead. Livewire is used to paralyze next Pokemon your opponent sent. It will help your next battle, but not the current one.
DVenusaur:
Try to get a nature that reduces attack stats, especially example Bold or Modest.
Moonblast and Draining Kiss are redundant. If recovery is your problem, use Leech Seed + Substitute instead.
Psybeam is USELESS if you already have Psychic. Psycho Boost can be used instead if you don’t plan to use the combo mentioned above. However, using Psycho Boost will lower its special attack significantly, so use it only if you plan to switch out.
Other option including Calm Mind or Charged Beam to boost special attack. Calm Mind also increases special defense, but adding Charged Beam can hit more Pokemon super effectively.
Excadrill:
Excadrill will not use special attack, so get a nature that lowers it. For excadrill, Jolly or Adamant is preferred.
Excadrill learns Rock Slide. Definitely use it instead of Drill Run. If you’re afraid about using Earthquake in double battle, replace Earthquake instead. Another solution is use Protect in your other Pokemon.
Change Metal Claw into Custom Move Steel, or Iron Head if you want to breed.
Samurott:
Get a Megahorn instead of Slash. Megahorn is learned via Heart Scale.
Aqua Jet instead of Brine. Aqua Jet has higher priority and it is very useful as your Samurott lacked in speed (proven with Brave nature).
Equip it maybe with Mystic Water if you need more power in Aqua Jet and Razor Shell.
DScizor:
Option 1:
Night Slash + Psycho Cut + (one Fighting move) have perfect neutral coverage. Absolutely have three of those. Last slot can be Icicle Crash for strong Ice attack, Hone Claws if you use Cross Chop to boost accuracy, or Ice Shard to fight faster opponent.
Option 2:
Always crit DScizor, equipped with Scope Lens, Focus Energy, Night Slash, Psycho Cut, and Cross Chop. This set doesn’t have Ice element attack but its attack can’t be resisted.