>>47811562I recently won all contests and got all the paintings in the Lilycove museum. Without going into great detail, here is what you need to know:
1. The berries from the berry master's wife make the best pokeblocks. Each of those five berries makes a block that corresponds to one of the five conditions. I fed each of my contest mons five blocks for the desired condition, and one block for a complimentary condition. Do your own research on conditions, pokeblocks and natures, sheen etc. I can't be bothered to type it all out here but it's not as complicated as it first appears. Basically what you want is a pokemon with a nature that allows it to happily eat pokeblocks that boost the condition of the contest you want to enter it in.
2. It's not super important what pokemon you use for each contest, as long as their move pool includes combos for the condition of the contest. I.e., if you're competing in the smartness contest, you need a mon that can learn two moves that form a combo. I think psypokes has a list of combos. Again I can't be bothered to go into more detail but it's all online.
3. If you really want a list of mons that are guaranteed to work, the pokemon I used in each contest were:
1. Cool - Chickorita (need to complete the Hoenn dex to get a Johto starter)
2. Smart - Kirlia
3. Beauty - Whiscash
4. Tough - Steelix (traded with FR for Onix)
5. Cute - Azurill
I didn't win every contest on my first try with these mons but I tried each contest a few times and eventually I got lucky and won. You need to not only win, but also win with a very high score to get all the paintings.
p.s. Ignore the idiots claiming you can use one pokemon and spam the same two moves to win all contests. They have never won all of the paintings without hacks and don't know what the fuck they're talking about.