Yamcha is a genuine lead only in the first series; after that he becomes the supporting player left behind while everyone else soars. Yamcha's profile covers the character; here we follow him arc by arc, from the desert where he steals capsules to the baseball game in Super, where for once he is the hero.
Dragon Ball
Emperor Pilaf Saga (episodes 1-13)
He debuts in episode 5 as a desert bandit with his loyal Puar: he tries to rob Goku and gives the starving kid real trouble, but the moment he sees Bulma he bolts, because girls terrify him. In the Emperor Pilaf Saga he tails the group to grab the Dragon Balls and wish his shyness away, until he ends up siding with them against Pilaf. At the castle he grabs the tail of Goku's Great Ape form so that Puar can cut it off. His long story with Bulma starts here.
21st Tournament Saga (episodes 14-28)
In the 21st Tournament Saga he breezes through the preliminaries, but his first opponent is a mysterious old man. In episode 22 Jackie Chun shrugs off his Wolf Fang Fist and blows him out of the ring with a gust of air.
Fortuneteller Baba Saga (episodes 69-83)
In the Fortuneteller Baba Saga he joins the team taking on the fortuneteller's fighters. In episode 71 he beats the invisible man thanks to Krillin's trick and Master Roshi's nosebleed; in episode 72, though, the Mummy is far too strong and flattens him.
22nd Tournament Saga (episodes 84-101)
After three years of training with Roshi, in the 22nd Tournament Saga he draws Tien right away. In episode 88 he throws an upgraded Wolf Fang Fist and a Kamehameha, but the Crane Hermit's student knocks him out and breaks his leg after the match is already over. By the end of the tournament a changed Tien asks for his forgiveness.
King Piccolo and Piccolo Jr. Sagas (episodes 102-153)
Still injured, he sits out the war against King Piccolo. In the Piccolo Jr. Saga he returns to the 23rd tournament with a new technique, the Spirit Ball, but he faces the odd Shen, who is Kami in disguise: in episode 139 Yamcha lands a direct hit and still loses, accepting defeat.
Dragon Ball Z
Saiyan Saga (episodes 1-35)
The anime turns him into a baseball star: in episode 10 Krillin pulls him out of a game to tell him Goku is dead and take him to train with Kami. In the Saiyan Saga he asks to fight in Krillin's place and beats a Saibaman, which then latches onto him and self-destructs: he dies in episode 23, the first of the fallen.
Frieza Saga (episodes 36-107)
In the Frieza Saga he is in the afterlife on King Kai's planet, where in episode 55 he works through the trials against Bubbles and Gregory with Tien. The anime also gives him some payback: in episode 95 he and the other fallen fighters beat the Ginyu Force members who have landed in the other world. He is revived with the Namekian Dragon Balls.
Androids and Cell Sagas (episodes 118-194)
In the Androids Saga he is the first to spot the Androids in the city, and in episode 126 Android 20 drives a hand through his chest. A senzu bean saves him, and he takes the heart-sick Goku home. By now his relationship with Bulma is over, and she will end up with Vegeta. In the Cell Saga he attends the Cell Games and, in episode 184, gets beaten down by a Cell Junior like nearly all his friends.
Majin Buu Saga (episodes 200-291)
In the Majin Buu Saga he has quit fighting and goes to the 25th tournament as a spectator. Sheltering at Kami's Lookout, in episode 260 he is turned into chocolate and eaten by Buu along with the others. Revived by the Dragon Balls, he gives his energy to the Spirit Bomb. In GT he only makes two brief cameos.
Dragon Ball Super
Battle of Gods Saga (episodes 1-18)
At Bulma's party, in the Battle of Gods Saga, he is far too chummy with Beerus, to Vegeta's horror, as episode 6 shows.
Future Trunks Saga (episodes 47-76)
His moment arrives in the Future Trunks Saga, with the baseball game between Universes 7 and 6 in episode 70. He names himself captain, strikes out the opposing batters with a pitch built on his own techniques and, amid the brawl between Beerus and Champa, steals home for the winning run.
In the Universe Survival Saga he is keen on the Tournament of Power, but Goku never picks him. In the Super manga, when Moro invades Earth, he is back in action and struggles badly against Zauyogi even with Tien and Chiaotzu's help. In Daima he has a new Japanese voice, Ryōta Suzuki, replacing Tōru Furuya.
Did you know? After the winning run Yamcha lies on home plate in the very pose he struck when the Saibaman killed him, and Krillin spots it at once.
Our take
Followed arc by arc, Yamcha shows Dragon Ball's change of scale better than any power chart. In the first series he is a credible opponent, then a good student who keeps meeting the wrong rival at the wrong time: Jackie Chun, Tien, Kami. The Saiyans settle the account with an explosion, and from then on Yamcha is a spectator.
Super deserves credit for realizing the character works best away from cosmic battles: the baseball game is an affectionate bit of payback, written for fans who always rooted for him.
For a wider view, revisit the profiles of Bulma, his longtime girlfriend, Tien, the rival who became a friend, and Krillin, his training partner. To follow their stories arc by arc too: Bulma saga by saga and Tien saga by saga.