Mysterious Treasures is a set in the Diamond & Pearl series. It was released on August 1, 2007. The printed size is 123. This checklist is longer, at 124 cards. Aggron is 1/123, in position 1 of 124 on this checklist. The next card is 2 Alakazam. The listed rarity is Rare Holo.
Aggron is a Stage 2 Metal Pokémon with 130 HP. The card lists level 49. In the Pokédex this is Aggron (#306), generation 3 (Hoenn). The card says it evolves from Lairon. In this catalog that name is Lairon (#305).
Kouki Saitou illustrated this card. The same name is on 652 other cards in the catalog.
Aggron (#306) has 23 other cards in the catalog. Those other cards are in 19 sets. The other printings with a release date run from 2003 to 2024. The earliest other card is Aggron 1/109 in Ruby & Sapphire (2003). That card lists 110 HP, and this one lists 130 HP. Both list the rarity Rare Holo. Mitsuhiro Arita illustrated that card, and Kouki Saitou illustrated this one. 22 other cards of Aggron list a different HP.
The attack Heap Up lists 40+ damage. The cost is Colorless, Colorless. Search your discard pile for all Energy cards and show them to your opponent. If you find any Metal Special Energy cards there this attack does 40 damage plus 30 more damage. Put all of those Energy cards on top of your deck. Shuffle your deck afterward. Hard Metal is another attack lists 60+ damage. The cost is Metal, Metal, Metal, Metal. You may do 60 damage plus 40 more damage. If you do, Aggron does 40 damage to itself. Weakness is Fire +40. Resistance is Psychic -20. Retreat cost is 4. The flavor text reads "While seeking iron for food, it digs tunnels by breaking through bedrock with its steel horns."
I keep a set binder for Mysterious Treasures, meant to hold every card of that set. This card is one slot in the Mysterious Treasures set binder. A generation binder holds one card of each species. Aggron can fill a slot in Generation 3 binder (Hoenn). I still need this card.