Combos are not preset. Figure out more difficult ones on your own. Otherwise, here's my ideas:
-1v1 For Fun. I don't like being forced to play 4-player matches in For Fun. It's not very fun if I can ONLY play in one such way.
-More Songs per stage. Could be decided by pressing R to toggle through the songs, the background shadow could change color to: Black (Default Song), Red (Second Song), Blue (Third Song) and/or Green (Fourth song). Music doesn't really take up much space, and it's rather annoying that I can't listen to Boss Battle 1 on the Reset Bomb forest. Chapter 12 and Dark Pit's Theme are good, fun songs, but Boss Battle 1 is actiony and fast-paced: Perfect for a Fighting Game.
-I'd like Dark Pit to become Luigified with these patches. It can start out as small things like changing him to be truly slower and stronger than Pit (He's carrying an Electroshock Arm, Guardian Orbitars, a Silver Bow, and his Dark Pit Staff. He should be slower than Pit, who carries two speed-boosting weapons on him), and then eventually gain his own moves, like Falcon Kicking for his Down Aerial and Dash Attacks. Lucina herself needs to have the Melee Shield Breaker animation. Not only would it be cool to see it back, it would also further show how she looks up to Marth and how much she's taken after him while still being her own person. Plus, the Parallel Falchion's power is balanced throughout the blade instead of at the tip, so there's that.
-Downloadable stages. I want a Temple II dang it!
-Stamina mode returns just the same from Brawl. I can't stand being limited to Stock and Time only. It's all the fault of Smash Run!
-I want one of these patches to give me the ability to see the Palutena's Guidance conversations on the Reset Bomb Forest stage, even on FD form. I want to be able to hear these myself in the middle of battle, just like in Kid Icarus: Uprising itself. Or, it would be interesting to hear some other things on the 3DS version as well. For example, hearing a conversation about Dark Pit going off on Sakurai for making him a blatant clone when he can be unique.
....That's pretty much it. Honestly, the only ones I feel are possible are the 3 songs per stage and the return of Stamina Mode as it was in Brawl. It's rather ridiculous that Boss Battle 1 isn't hearable in the KI: U stage on the 3DS version. Blasphemy I tell you.