It's pretty self explanatory. Out of interest I searched the internet for some results on what everyone enjoys using. Whether it be for OP status, generally fun to use, or because they like the Pokémon. It's based on MD:Sky, not MD:Time/Darkness, because there are more options and MD:Sky essentially a 'successor/additional stuff' version of the other two.
I searched to see if this exists on Reborn, but I couldn't find anything (or on the internet as an actual poll, either)
------------------------My favourites----------------------------
Hero:
Eevee: I admit it's just because I'm an Eevee fan (what gives that away...?) but she is pretty fun to use in the game as a hero anyways. If Adaptability Tackle/Quick attack is resisted then you go all dig/shadow ball on them
Partner:
Pikachu. It's a tough one, but I like Pikachu in the mystery dungeon games. Shock wave is satisfying to watch, and the obvious choice of OP Discharge wrecks a lot of late-game troubles.
(Hey... Nidoqueen's spam Earth power so why can't I spam discharge ;D)
Special mentions:
Cyndaquil: My first game on Red was with Cyndaquil and I really enjoyed watching my baby grow up with his partnered Pikachu by his side. Also, Typhlosion looks like it has some anger problem in this game! Mudkip: Just another game I remember playing. It was a fun game. I forgot who the partner was, though... maybe Chikorita?
(Sorry for the terrible formatting of this post. If anyone has advice on nice looking posts then fire away!!! My posts always look ugly for some reason.. :c)