AttackBellow
Flip a coin. If heads, the Defending Pokémon is now Paralyzed.

Gym Heroes is a set in the Gym series. It was released on August 14, 2000. The printed size is 132, and the checklist is the same length. Brock's Onix is 69/132, in position 69 of 132 on this checklist. Before it is 68 Brock's Mankey, and after it is 70 Brock's Rhyhorn. The listed rarity is Common.
Brock's Onix is a Basic Fighting Pokémon with 100 HP. The card lists level 41. In the Pokédex this is Onix (#095), generation 1 (Kanto). The card lists Steelix, Steelix (#208) under evolves to.
Ken Sugimori illustrated this card. The same name is on 1,112 other cards in the catalog.
Onix (#095) has 29 other cards in the catalog. Those other cards are in 28 sets. The other printings with a release date run from 1999 to 2025. The earliest other card is Onix 56/102 in Base (1999). That card is named Onix, while this one is Brock's Onix. That card lists 90 HP, and this one lists 100 HP. Both list the rarity Common. 25 other cards of Onix list a different HP.
The attack Bellow lists no damage number. The cost is Colorless. Flip a coin. If heads, the Defending Pokémon is now Paralyzed. Rock Throw is another attack lists 30 damage. The cost is Fighting, Fighting, Colorless. Weakness is Grass ×2. Retreat cost is 3.
I keep a set binder for Gym Heroes, meant to hold every card of that set. This card is one slot in the Gym Heroes set binder. A generation binder holds one card of each species. Onix can fill a slot in Generation 1 binder (Kanto). Themed lists that include this exact card are Trainer's Pokémon, Kanto Gym Leaders and their Pokémon, and Brock and his Pokémon. I still need this card.
Flip a coin. If heads, the Defending Pokémon is now Paralyzed.
Gym Heroes, in the Gym series. It was released on August 14, 2000. The printed size is 132.
69/132. It is entry 69 of 132 in this checklist.
Ken Sugimori. The catalog lists 1,112 other cards with that illustrator.
Common.
Onix #095, generation 1 (Kanto).
Bellow and Rock Throw (30).