Pyro
Power Star
So, this game's items have "types". If you use a normal-type item on the Ghost-type, nothing will happen. If you use a Fighting-type item on the Physcic-type, it will do half the damage. If you use a Bug-type item on the Dark-type it will do double damage.
Don't know the types? http://bulbapedia.bulbagarden.net/wiki/Type_chart
All items inflict 4 damage unless noted.
Items
5th Post: Tackle
10th Post: Bullet Punch
15th Post: Acrobatics
20th Post: Toxic (damages target by 1 point for 10 posts)
25th Post: Volt Switch (secondary effect: switches the Electric-type with another type on the list)
30th Post: Water Gun
35th Post: Shadow Ball
40th Post: Crunch
45th Post: U-turn (same effect as Volt Switch)
50th Post: Leaf Blade
55th Post: Psybeam
60th Post: Earthquake
65th Post: Rock Slide
70th Post: Ice Beam
75th Post: Dragon Pulse
80th Post: Superpower (Hurt x8)
100th Post: Fire Blast (Hurt x10)
Normal: 30
Fighting: 30
Flying: 30
Poison: 30
Ground: 30
Rock: 30
Bug: 30
Ghost: 30
Steel: 30
Fire: 30
Water: 30
Grass: 30
Electric: 30
Psychic: 30
Ice: 30
Dragon: 30
Don't know the types? http://bulbapedia.bulbagarden.net/wiki/Type_chart
All items inflict 4 damage unless noted.
5th Post: Tackle
10th Post: Bullet Punch
15th Post: Acrobatics
20th Post: Toxic (damages target by 1 point for 10 posts)
25th Post: Volt Switch (secondary effect: switches the Electric-type with another type on the list)
30th Post: Water Gun
35th Post: Shadow Ball
40th Post: Crunch
45th Post: U-turn (same effect as Volt Switch)
50th Post: Leaf Blade
55th Post: Psybeam
60th Post: Earthquake
65th Post: Rock Slide
70th Post: Ice Beam
75th Post: Dragon Pulse
80th Post: Superpower (Hurt x8)
100th Post: Fire Blast (Hurt x10)
Normal: 30
Fighting: 30
Flying: 30
Poison: 30
Ground: 30
Rock: 30
Bug: 30
Ghost: 30
Steel: 30
Fire: 30
Water: 30
Grass: 30
Electric: 30
Psychic: 30
Ice: 30
Dragon: 30