Let's get a thread about things you want back in pokemon games, and why they should be back.

Hard Mode: No Trainer Customization
Dante Must Die Mode: No Pokemon following you.

I'm sure a lot of you don't even remember this feature, but it was a big one to me. It helped individualize your pokeballs and was a fun pastime, what with the collecting of unowns and all.
For those who don't know, read up here: http://bulbapedia.bulbagarden.net/wiki/Seal