So I continued my adventure, first on my Diamond game. I'm now playing Pearl, and after that I'll let Platinum catch up.
What I've done is the following: I walked to Oreburgh City, beating some trainers along the way and some hiker gave me HM06. I wanted to challenge the gym, but had to fetch the gym leader, Roark, first. I did that, and demolished Roark with Turtwig/Milotic/Piplup. Afterwards I caught all the Pokémon I could catch, traded where I could and got all the items. Then I went back to Jubilife, had my first encounter with Team Galactic, beat them, beat the trainers on the lower part of route 204 and healed my Pokémon in Jubilife Pokémon Center, which is where I saved my game.
Seed Bomb, Tackle, Absorb, Withdraw
Surf, Ice Beam, Psychic, Calm Mind
Thunderbolt, Signal Beam, Grass Knot, ThunderShock
Pursuit, Drill Peck, Heat Wave, Thunder Wave
Scratch, Fire Punch, Brick Break, Swords Dance
Shadow Ball, Thunderbolt, Sucker Punch, Nasty Plot
Surf, Ice Beam, Water Pulse, Splash
Quick Attack, Return, Aerial Ace, U-Turn
Surf, Ice Beam, Pound, Bubble
Aerial Ace, Earthquake, Rock Slide, Swords Dance
Thunderbolt, Shadow Ball, Signal Beam, Thunder Wave
Scratch, Brick Break, Fire Punch, Seed Bomb