Only a few things to watch out for, no matter what Partner Pokémon you choose. you want to reduce the amount of fights you have to do to the minimum, this is affected in the ranking phase of the tournaments.
Look at the rankings of the NPCs you'll fight, the lowest ranking is the ranking you land on after those 5 Fights. if you dislike the ranks, you can just cancel out and re-enter. (you want to go down in ranks about 20 ranks each time)
if you wanna go at it advanced, you an also look at the Pokémon you'll fight, some Pokémon are faster to KO than others, so watching out to get a favourable opposition is a thing to do. (guardevoir for example is really fast to defeat)
I hope that helps somewhat.
~HDK
edit: ez world rekky choose Chandelure, 5p4m laz0r b34m.
