Hey kids, want to know a secret to earning battle points quickly that I discovered? Well check this out then:
Shedinja RULES in the Battle Palace.
Shedinja
Adamant nature
-Shadow Ball
-Confuse Ray
-Secret Power
-Fury Cutter
is the set I use. It may not look good right now, but it's surprisingly useful. Had I known that it would've been useful, I would've bred for Silver Wind, since Fury Cutter is absolutely useless and Secret Power isn't all that helpful, but it needs something stronger to hit Normal types. Luckily it doesn't use Fury Cutter very often though.
Anyway, the reason it's so helpful is because if your opponent's first pokemon is something that would be screwed against Shedinja, they'll switch it out to something else, something that's likely to have a move that'll defeat Shedinja. If you decide to keep it out for a while, it can actually work because the opponent's pokemon doesn't necessarily know what move to use, although it is usually a better idea to switch out. Then, when the opponent has no choice but to put their first pokemon back into battle, you know you'll be able to defeat it with Shedinja!
As for the pokemon to switch out to... I don't have that many Lv50 bred EV trained pokemon, but I do have these guys which I find useful:
Electabuzz
Quirky nature
-Thunderbolt
-Ice Punch
-Fire Punch
-Brick Break
Its stats aren't great, but it has a great movepool for an electric type. It is helpful at knocking out pokemon such as Swellow and other flying types that would normally kill Shedinja.
Slowbro
Quirky nature
-Surf
-Psychic
-Yawn
-Amnesia
Unfortunately I find it using Amnesia a lot despite its nature, so I will be replacing it with Ice Beam soon and getting rid of Electabuzz for something a little stronger. Generally, any relatively defensive water types should do the job just as well, and the ability to survive Shadow Ball and Crunch/Bite/Pursuit would be helpful too.
So, going over Shedinja's movepool, I'd say that this would be the best set to use:
Shedinja
Adamant nature
-Shadow Ball
-Confuse Ray
-Silver Wind
-Return/Aerial Ace
Be aware that you need to breed with a male Butterfree to get Silver Wind.
The reasons that I didn't breed for the above moveset are 1: I didn't know that Silver Wind would be helpful, and 2: I'm not trying to beat the leaders right now, I'm only trying to earn extra battle points quickly to use the move tutors and get the other prizes.