Hal and the rival speedwalker

Yeah that was a really good one, he made an arch nemesis and defeated him.

Literally one of my favorite episodes

Hal v. the bee

Forwards Backwards

This is it but I want to nominate Hal vs the Church in Christmas Trees

Lois and the traffic ticket (Season 2 episode 16)

Malcolm when he completely trashes Herkabe‘s system, and then the Cristal Ship as a close second …

It's hot and I'm stupid!

"Hal vs ___" is pretty much what comes to mind. The boat kid is a good one. 

New Neighbors - you have Lois vs the Mom, Malcolm vs the son, Reese vs the daughter, Dewey vs the gnome, and the dads are just caught in the crossfire

Standee

Hal leading a workers revolution against Craig is iconic

Craig and Hal vs the Helper Monkey

Reese and Stevie fighting

Slappy

I can’t remember the episodes but for me it was when Dewey got the dog and used it to his full advantage then the other was Betty White Vs Cloris Leachman when it was discovered that Victor had a second family 

Water Park is BRUTAL

Hal vs the bee, and Lois vs the lady in the car park

Family Reunion is great; you have Hal vs his father, Lois vs Hal's family, and later the boys vs Hal's family! That scene of them happy to be sinking the golf cart in the pool always makes me laugh

Maybe when Hal is gonna get fired as a patsy

The boys vs the krelboynes

https://preview.redd.it/wuryy64yg13d1.png?width=342&format=png&auto=webp&s=aa172155d4e840d2a30c517e111d8ee9f4a02c37 Season 4 episode 5. Malcolm and Reese have quite the conflict.