Help me decide which mons to go forward with

My team currently consists of Venusaur (Delta), Feraligatr, Lucario, Delta Gardevoir, and Flygon (-SpA nature so I am not going to mega evolve him). I am around mid-level 40s and about to fight Audrey at the whirl islands (just to clarify where I am in the game for better recommendations)
First of all, I wonder whether I should go forward with Feraligatr, or change to greninja or a different mon.
Secondly, what should be my next Mon. If delta quagsire is really that good (assumption because it costs 9999 coins), then I will buy him as I do have a way of grinding coins. There are also some deltas I missed like delta budew. I also have a delta scyther at the daycare if I want to get him.
Thanks for the help in advance

Replace Flygon when you can with a Garchomp if not going Mega since Garchomp is literally better in every way.
Don’t bother with Greninja unless you get one with Protean which is in slot 2 from Friend Safari so you will need 6 badges, Quagsire isn’t any good.
You are really close to a hidden grotto with Delta Combee which turns into Delta Vespiqueen and is very good.
Delta Haxorus is also an option to replace Feraligatr

Thanks for the help! Looking at a future team being
Mew (I have)
Delta Haxorus (Going to get)
Delta Gardevoir
Mega Hydreigon (Going to get shiny deino from brodcast tower)
Armored TTar (Going to get just cuz it seems good)
Delta Bisharp (have and can mega)
Not going to use vespiqueen because bisharp has blaze kick and delta haxorus has steel type.