I'm trying to work out what each set logo is supposed to be or what it's supposed to look like, but I'm really puzzled by some set logos! Some are straight forward, while others look like odd shapes.
Base Set: Nothing.
Jungle: Vileplume's flower.
Fossil: A skeletal foot.
Base Set 2: Number 2, with a Poké Ball on top.
Team Rocket: Capital R; Team Rocket's logo.
Gym Heroes: Big logo looks like Silver Wing, but only one branch.
Gym Challenge: Big logo looks like Silver Wing, but only one branch.
Neo Genesis: A star over lapped by another star.
Neo Discovery: Ruins.
Neo Revelation: A water splash or Entei, Raikou and Suicune coming out of Burned Tower.
Neo Destiny: Blue star-like shape with a light grey shadow.
Legendary Collection: A ring?
VS: Large, blue "VS".
Web: Large, blue "Web".
Expedition: Lower case "e", with a circle in the middle. Japanese version has a "1" in the circle.
Aquapolis: A building-like structure in a black tear-drop like shape, with a white outline. Japanese version has the same logo as Expedition, but with a "2" or "3" in the circle.
Skyridge: Two mountains and one has a halo. Japanese version has the same logo as Expedition, but with a "4" or "5" in the circle.
EX Ruby & Sapphire: Sparkling gem.
EX Sandstorm: TBH, I always though it was Meowth's charm and paw.
EX Dragon: Steering wheel? Dragon's eye? Lantern?
EX Team Magma vs Team Aqua: Red and blue X shape.
EX Hidden Legends: Regi-like cave from the outside and from a bird's-eye view.
EX FireRed & LeafGreen: Simplistic Poké Ball-like shape. Japanese version has three pinwheel-like blades.
EX Team Rocket Returns: Capital R on a shield/badge.
EX Deoxys: Crudely drawn shooting star.
EX Emerald: Horizontal rectangular gem.
EX Unseen Forces: Ho-Oh's wing crossed with Lugia's wing.
EX Delta Species: Holon Tower?
EX Legend Maker: Three pine/spruce trees?
EX Holon Phantoms: Holon Lake monuments from a bird's-eye view.
EX Crystal Guardians: A line?
EX Dragon Frontiers: Two mountains near the sea.
EX Power Keepers: Two parts of the radioactive logo and the top part is replaced by 5 points.
Diamond & Pearl: Crudely drawn gem. Japanese version has "DP1" instead of a shaped logo.
Mysterious Treasures: 10-point star, in a black circle. Japanese version has "DP2".
Secret Wonders: Swirls. Japanese version has "DP3".
Great Encounters: ??? Japanese version has "DP4".
Majestic Dawn: Crudely drawn sun rising over the horizon. Japanese version has "DP4".
Legends Awakened: ??? Japanese version has "DP5".
Stormfront: Yin Yang-like shape. Japanese version has a Gracidea flower.
Platinum: Vaguely looks like Giratina Origin from above. Japanese version has "Pt1".
Rising Rivals: ??? Japanese version has "Pt2".
Supreme Victors: ??? Japanese version has "Pt3".
Arceus: Has a smaller, more simplistic version of the ripple effect on Arceus' cards or is meant to look like Arceus' wheel thing from head on. Japanese version has "Pt4".
HeatGold & Soul Silver: Ambiguous gold and silver shapes. Japanese version has a weird looking upside-down flipped 7, next to a normal looking "1".
Unleashed: Kartana-like shape (though, since this set was made WAY before Kartana was even though of, I have no idea of what it's actually meant to be).
Undaunted: Similar looking to Noble Victories' set logo, but the "V" shape is flipped and there's a part that curves down off of the upper right of the "V" shape. Japanese version has an upside down flipped 7, next to a normal looking "2".
Triumphant: Two white crowns touching bases, in a black circle. Japanese version has an upside down flipped 7, next to a normal looking "3".
Call of Legends: Two curved shapes, connected in the middle.
Black & White: Black and white checked pattern. Japanese version has "BW1".
Emerging Powers: ???
Noble Victories: Victini's ears. Japanese version has "BW2".
Next Destinies: ??? Japanese version has "BW3".
Dark Explorers: Black heptagon shape, with a white, almost oval-like shape taken out of the top. Japanese version has "BW4".
Dragon Vault: Serpentine-like shape. Japanese version has "DS".
Dragon's Exalted: Two shapes that almost look like the Dragon Type Energy logo. Japanese version has "BW5".
Boundaries Crossed: Snowflake-like shape; half of it is white on a black background, while the other half is black on a white background. Japanese version has "BW6".
Plasma Storm: Plasma-like shield logo, with alternating black and white stripes, that start from the middle. Japanese version has "BW7".
Plasma Freeze: Hexagonal shape with white strips going down the left side. Japanese version has "BW8".
Plasma Blast: Genesect's head from above. Japanese version has "BW9".
Legendary Treasures: Meteor-like shape. Japanese version has "EBB".
XY: Heart-like shape with an X. Japanese version has "XY1".
Flashfire: Flames or antlers from the side. Japanese version has "XY2".
Furious Fists: Strange looking fist or boxing glove. Japanese version has "XY3".
Phantom Forces: ??? Japanese version has "XY4".
Primal Clash: Snorunt-like shape. Japanese version has "XY5".
Roaring Skies: ??? Japanese version has "XY6".
Ancient Origins: Segmented ring, presumably warping something. Japanese version has "XY7".
BREAKthrough: ??? Japanese version has "XY8".
BREAKPoint: 3 points in a black circle. Japanese version has "XY9".
Generations: English version has the Kanji for "20". Japanese version has English for "20th".
Fates Collide: Looks like Mega Alakazam's head, without any facial hair. Japanese version has "XY10".
Steam Siege: Time Gear-like object. Japanese version has "XY11".
Evolutions: Almost looks like Magnemite. No Japanese set logo.
Sun & Moon: Half of a sun, next to a half moon. No Japanese set logo.
Guardians Rising: Almost looks like a Tapu logo. No Japanese set logo.
Jungle: Vileplume's flower.
Fossil: A skeletal foot.
Base Set 2: Number 2, with a Poké Ball on top.
Team Rocket: Capital R; Team Rocket's logo.
Gym Heroes: Big logo looks like Silver Wing, but only one branch.
Gym Challenge: Big logo looks like Silver Wing, but only one branch.
Neo Genesis: A star over lapped by another star.
Neo Discovery: Ruins.
Neo Revelation: A water splash or Entei, Raikou and Suicune coming out of Burned Tower.
Neo Destiny: Blue star-like shape with a light grey shadow.
Legendary Collection: A ring?
VS: Large, blue "VS".
Web: Large, blue "Web".
Expedition: Lower case "e", with a circle in the middle. Japanese version has a "1" in the circle.
Aquapolis: A building-like structure in a black tear-drop like shape, with a white outline. Japanese version has the same logo as Expedition, but with a "2" or "3" in the circle.
Skyridge: Two mountains and one has a halo. Japanese version has the same logo as Expedition, but with a "4" or "5" in the circle.
EX Ruby & Sapphire: Sparkling gem.
EX Sandstorm: TBH, I always though it was Meowth's charm and paw.
EX Dragon: Steering wheel? Dragon's eye? Lantern?
EX Team Magma vs Team Aqua: Red and blue X shape.
EX Hidden Legends: Regi-like cave from the outside and from a bird's-eye view.
EX FireRed & LeafGreen: Simplistic Poké Ball-like shape. Japanese version has three pinwheel-like blades.
EX Team Rocket Returns: Capital R on a shield/badge.
EX Deoxys: Crudely drawn shooting star.
EX Emerald: Horizontal rectangular gem.
EX Unseen Forces: Ho-Oh's wing crossed with Lugia's wing.
EX Delta Species: Holon Tower?
EX Legend Maker: Three pine/spruce trees?
EX Holon Phantoms: Holon Lake monuments from a bird's-eye view.
EX Crystal Guardians: A line?
EX Dragon Frontiers: Two mountains near the sea.
EX Power Keepers: Two parts of the radioactive logo and the top part is replaced by 5 points.
Diamond & Pearl: Crudely drawn gem. Japanese version has "DP1" instead of a shaped logo.
Mysterious Treasures: 10-point star, in a black circle. Japanese version has "DP2".
Secret Wonders: Swirls. Japanese version has "DP3".
Great Encounters: ??? Japanese version has "DP4".
Majestic Dawn: Crudely drawn sun rising over the horizon. Japanese version has "DP4".
Legends Awakened: ??? Japanese version has "DP5".
Stormfront: Yin Yang-like shape. Japanese version has a Gracidea flower.
Platinum: Vaguely looks like Giratina Origin from above. Japanese version has "Pt1".
Rising Rivals: ??? Japanese version has "Pt2".
Supreme Victors: ??? Japanese version has "Pt3".
Arceus: Has a smaller, more simplistic version of the ripple effect on Arceus' cards or is meant to look like Arceus' wheel thing from head on. Japanese version has "Pt4".
HeatGold & Soul Silver: Ambiguous gold and silver shapes. Japanese version has a weird looking upside-down flipped 7, next to a normal looking "1".
Unleashed: Kartana-like shape (though, since this set was made WAY before Kartana was even though of, I have no idea of what it's actually meant to be).
Undaunted: Similar looking to Noble Victories' set logo, but the "V" shape is flipped and there's a part that curves down off of the upper right of the "V" shape. Japanese version has an upside down flipped 7, next to a normal looking "2".
Triumphant: Two white crowns touching bases, in a black circle. Japanese version has an upside down flipped 7, next to a normal looking "3".
Call of Legends: Two curved shapes, connected in the middle.
Black & White: Black and white checked pattern. Japanese version has "BW1".
Emerging Powers: ???
Noble Victories: Victini's ears. Japanese version has "BW2".
Next Destinies: ??? Japanese version has "BW3".
Dark Explorers: Black heptagon shape, with a white, almost oval-like shape taken out of the top. Japanese version has "BW4".
Dragon Vault: Serpentine-like shape. Japanese version has "DS".
Dragon's Exalted: Two shapes that almost look like the Dragon Type Energy logo. Japanese version has "BW5".
Boundaries Crossed: Snowflake-like shape; half of it is white on a black background, while the other half is black on a white background. Japanese version has "BW6".
Plasma Storm: Plasma-like shield logo, with alternating black and white stripes, that start from the middle. Japanese version has "BW7".
Plasma Freeze: Hexagonal shape with white strips going down the left side. Japanese version has "BW8".
Plasma Blast: Genesect's head from above. Japanese version has "BW9".
Legendary Treasures: Meteor-like shape. Japanese version has "EBB".
XY: Heart-like shape with an X. Japanese version has "XY1".
Flashfire: Flames or antlers from the side. Japanese version has "XY2".
Furious Fists: Strange looking fist or boxing glove. Japanese version has "XY3".
Phantom Forces: ??? Japanese version has "XY4".
Primal Clash: Snorunt-like shape. Japanese version has "XY5".
Roaring Skies: ??? Japanese version has "XY6".
Ancient Origins: Segmented ring, presumably warping something. Japanese version has "XY7".
BREAKthrough: ??? Japanese version has "XY8".
BREAKPoint: 3 points in a black circle. Japanese version has "XY9".
Generations: English version has the Kanji for "20". Japanese version has English for "20th".
Fates Collide: Looks like Mega Alakazam's head, without any facial hair. Japanese version has "XY10".
Steam Siege: Time Gear-like object. Japanese version has "XY11".
Evolutions: Almost looks like Magnemite. No Japanese set logo.
Sun & Moon: Half of a sun, next to a half moon. No Japanese set logo.
Guardians Rising: Almost looks like a Tapu logo. No Japanese set logo.