Well for the last slot you should definetly get some type of eeveelution whether it be Umbreon/Jolteon/Leafeon/Slyveon or honestly whatever your preference is just keep your team synergy in mind.
Hawlucha is a powerful choice suprised more ppl are not taking advantage of it, but you might want to get rid of the moves that hinder it like the comment above suggest.
Delphox should not have cut, shadow ball is a great sub and while having future sight can be helpful try and think of anything else that may become more handy than future sight, but if not then keep it.
As for Luxray even though its my favorite pokemon in the game, I know that its not the best electric type, i still recommend either using jolteon or catching a magneton(a steel typing also complements your team)
As for gyarados i also agree with the above comment
And finally for Golem while it is not a bad pokemon, there are better pokemon if you are willing to go Fossil Hunting but that's up to you, if you want to do the helix jobs you could end up with a dragon or ice type on your team which would give you some diversity and more coverage