Veemon

Veemon is a Rookie Level Small Dragon Digimon, one of the few "ancient-species". He is able to armor-digivolve by using Digi-Eggs.

Digimon Adventure 02: Tag Tamers
Veemon digivolves from DemiVeemon to ExVeemon in lines 1 and 22. With the Digi-Eggs of Courage, Friendship, and Miracles, Veemon can, for one round, digivolve to Flamedramon, Raidramon, and Magnamon, respectively.

Digimon Adventure 02: D-1 Tamers
Ryo Akiyama begins with a Veemon in his party, a reference to Digimon Adventure 02: Tag Tamers, where he is partnered to one.

Digimon Tamers: Brave Tamer
The Veemon card, titled "PF AP Plus III", is a Rank 2 card which increases a Digimon's AP by 120.

Digimon Frontier
Multiple Veemon were seen at the Autumn Leaf Fair.

Digital Monster D-Project
Veemon is the Rookie of the Dragon's Nest Area. The Devidramon in Area 5 will turn into a Veemon upon defeat, who will digivolve to ExVeemon with a Paildramon and Imperialdramon in his party to fight the player in the postgame.

Digimon Adventure V-Tamer 01
Veemon and Davis are sent to the V-Tamer world during a battle against Parallelmon, who had been kidnapping Tamers and their partners from various dimensions. There they meet Tai and Zeromaru, and Veemon shows off his Armor Evolutions while they track down Parallelmon. During the battle, Zeromaru and Veemon as Magnamon destroy Parallelmon, returning Davis, Veemon, and all of the captured Tamers to their respective dimensions.

Digimon World 2
Veemon can digivolve into Veedramon or Flamedramon. Veemon cannot be found in the wild, and can only be obtained by DNA Digivolving two Champion Digimon, such as Greymon and Airdramon.

Digimon World 3
Veemon is the only partner Digimon that is not available at the beginning. To obtain one as a partner, the player must get Veemon DNA from Paildramon, and then report to the DRI agent. Veemon is also sometimes seen in cities and in the Underground Network. The player can speak to him, but cannot battle him. He is also available as a card. He is a Rookie level Red-type with 4/4 stats and alongside Agumon is the second most powerful Rookie card (If you play three or more, you can summon Paildramon). The first time he can be found in Wind Prairie's exit to Kicking Forest. He will give you a sidequest for the tree kicking boots. To find him there you'll have to speak to the little boy kicking the trees in Plug Cape first.

Digimon World 4
Veemon is one of the four starter Digimon. Dorumon can digivolve to Veemon at Level 16. Veemon can digivolve into Guilmon at level 16.

Digimon Battle Spirit
Veemon appears as a default playable digimon who digivolves to Imperialdramon Paladin Mode and as a main enemy digimon in the "Desert" level.

Digimon Racing
Veemon is one of the three characters who are locked. Instead of digivolving to ExVeemon, Veemon armor digivolves to Flamedramon.

Digimon World Data Squad
http://digimon.wikia.com/wiki/User:Maitkarro/DW_Data_Squad#Veemon

Digimon World DS
Veemon digivolves from Chibomon, and can digivolve further into ExVeemon depending on its stats. He cannot be obtained in the wild, but must be matched over Wi-Fi to get the Serpent Egg, which hatches into Chibomon, then Veemon.

Digimon Rumble Arena 2
Veemon is one of the 13 Digimons that can be played at the start. He can digivolve to Flamedramon and Imperialdramon Fighter Mode.

Digimon World Dawn/Dusk
Veemon appears in Login Moutain in Dusk/Dawn

Veemon can digivolve into either Ex-Veemon or Veedramon depending on it's stats. You can Armor Digivolve Veemon to Flamedramon at Lvl 22 and with 2500 Dragon exp can Armor Digivolve with Digi-Egg of Courage, Magnamon at Lvl 40 and Holy Exp 10000 with DigiEgg of Miracles. Digivolves to ExVeemon Lv23 with 120 Attack and 115 Spirit. Digivolves to Veedramon Lv 18 with 90 Attack and 340 Dragon Exp.

Digimon World Championship
Veemon digivolves into Veedramon, Airdramon, Seadramon and Raremon, and digivolves from Tokomon and Koromon and can be found at S Bridge Valley.

Attacks 
 * Vee-Headbutt (V-mon Head): Charges and head-butts the opponent with tremendous force.
 * Vee-Knockout : Punches his opponent.
 * Vee-Punch (ブンブンパンチ): Veemon swings his arms and hits the opponent.
 * Hopping Kick

Notes and References
Veemon is the only digimon that can armor digivolve with every single digi-egg without turning into the same thing twice.