What was hard about hard was that they halved all of the expansions ( instead of 2 Super Missles per tank it gives you 1). Yeah… Drools… 
Omega Pirate. Boosrt Guardian. Some of the most insane bosses ever.
Metroid 2? Hard? It’s a straight line and every boss takes the same strategy.
Metroid 1? You’ll die a lot but rarely have to repeat anything, since it saves your progress anyway.
Bah. Super is still the easiest anyway.
Boost Guardian was tough. It took me like 7 tries before I could finally beat him.
Prime 2 I forgot! The bosses went from easy ( Amboris) to Hard ( Boost Gaurdian) In about eh…20 minutes! 
Edit: Metroid 2 hard… i ment I diddn`t beat it because it bored me to death. 
Phantasy star online 1&2 in ultimate mode.
I died about 7 times on Boost Guardian on my first run through MP2, and about 7 more times on my hard run. I’m fairly confident I could crush him on normal now though. I had a really tough time on DS4 for hard… 