I’d give Kingambit a go. You’ve already got plenty of Psychic damage, so I’d want that last slot to help when you can’t just click Expanding Force.
It gives you another physical attacker, something to take Ghost and Dark hits, and another Pokémon that likes being under Trick Room. Kowtow Cleave and Iron Head also let you keep attacking into Wide Guard.
I’d start with Sitrus Berry, Defiant, Brave, 32 HP / 32 Atk / 2 SpD, running Kowtow Cleave / Iron Head / Swords Dance / Protect. Indeedee can help you get a Swords Dance off with Follow Me, but don’t feel like you have to set up every time. Defiant also makes people think twice about bringing Intimidate into it.
Usually you’d consider Sucker Punch, but with Terrain Extender on Indeedee, I’d try this version first. Your own terrain blocks Sucker Punch against grounded targets. It can still be useful once terrain gets replaced or runs out, though.
The main thing I’d watch is Ground damage, since you’d have Kingambit, Sneasler and Armarouge sharing that weakness.
Also, try to keep Indeedee alive against Rillaboom. Terrain Extender gives you more turns, but it doesn’t stop them replacing your terrain. Being able to switch Indeedee back in is what gets your damage going again.
Kingambit would be my first test—you can keep Alakazam and Sneasler for faster games, then bring it alongside Hatterene or Armarouge when Trick Room looks better.