In Get the Show on the Road!, Blaziken was given to May by Professor Birch in Littleroot Town when it was still a Torchic. She chose it as her starter Pokémon because she thought Treecko was creepy and scary and Mudkip had attacked her earlier with a Water Gun in the face. However, she seemed to like Torchic's cute appearance and sweet nature.
In the next episode May used Torchic to try to catch her first wild Pokémon, an Azurill. Despite trying its best, the Azurill was too fast and agile for Torchic, easily dodging its attacks and causing Torchic to run into other objects. This eventually angers Torchic enough to fire an Ember attack, which hits not only Azurill but a Marill and Azumarill. They all simultaneously spray Water Gun at Torchic, knocking it out in one shot.
Due to being very immature and inexperienced May did not use Torchic very often, preferring Beautifly and Skitty.
In A Shroomish Skirmish, Torchic got separated from its Trainer and got lost alongside Ash's Corphish. Some wild Shroomish and a Breloom start attacking them, which causes Torchic to evolve into Combusken. Breloom challenges Combusken to hand-to-hand combat. Combusken obliges, and a vicious fight ensues. Both Pokémon are hit numerous times in the face by punches and kicks, and in the end a cross-counter knocks out both Pokémon.
After evolving into Combusken, it proved to be very useful for Pokémon Contests. The first time it took part of one was in Pokéblock, Stock and Berry and Lessons in Lilycove!, when May used it in the Lilycove Contest. Even though its Fire Spin caused problems during the Appeals Round, Combusken managed to get a score of 23.6, which helped May to reach the Contest Battles. After defeating Jessie and Chimecho, May had to battle Kelly, a fellow Pokémon Coordinator she met prior to entering the Contest. Kelly and her Grumpig showed great talent and effort, but May and Combusken turned out as the winners, earning them the Lilycove Ribbon.
When May got the five required Ribbons, she participated on the Hoenn Grand Festival, where Combusken was used in her quarter-finals battle round against Drew's Flygon and Roselia, alongside Skitty, in Rhapsody in Drew. Together, they managed to put up a great fight, but they were defeated, leaving May within the Top 8 Coordinators of the Festival.
During May's Kanto journey, Combusken had more appearances due to the Pokémon Contests allowing Coordinators to use different Pokémon for each round. In A Hurdle for Squirtle, Combusken was used for the Appeals Round of the Saffron City Contest, where it used Fire Spin and Sky Uppercut on May's untied bandanna to knot it back to her head. Later on, in Weekend Warrior, it was used for the battle rounds of the Silver Town Pokémon Contest. May and Combusken faced Coordinator Jeremy and his Venusaur in the final match; after a really close battle, where the Grass type used the powerful Frenzy Plant attack, May and Combusken ended as the winners, earning them the Ribbon.
In Spontaneous Combusken, it was used once again for the battle rounds, this time in the Chrysanthemum Island Convention. May and Combusken first faced Jessie and Mime Jr.. Though Mime Jr. was able to Mimic Combusken's Fire Spin and hit it with the unusual Tickle attack, Combusken managed to land a Sky Uppercut through the opposing Fire Spin and win the battle. In the second battle, Combusken was seen beating a Skarmory with Quick Attack. In the final battle, May and Combusken faced Brianna and her Vibrava. After being weakened by Screech, Combusken managed a Fire Spin, however it was countered by Dragon Breath. It was then trapped by Vibrava's Sand Tomb and remained immobilized while May's points decreased, until it broke out with a new move: Mega Kick. Combusken was then able to swiftly win the match and May received her third Ribbon.
Finally, in New Plot, Odd Lot!, Combusken was used for the Appeals Round of the Mulberry City Pokémon Contest. Team Rocket, who banded together with May's rival Harley, attempted to ruin her performance: Harley loaned James and Meowth his Ariados to sabotage May's appeal and kick her out of the Contest, so she would not get the last Ribbon she needed to get into the Grand Festival; however, surprisingly, their plan backfired when Combusken's Fire Spin started enveloping Ariados' web, going upwards in a spiral manner, not only setting Combusken free from it, but also surprising all three judges in the process. May managed to advance to the battle rounds (narrowly, though), and went on to defeat Jessie, who this time had borrowed Harley's Banette, in the final round.
For the Kanto Grand Festival, Combusken was used for one of the Appeals Rounds and two of the battle rounds. Its appeal performance during May, We Harley Drew'd Ya!, just like the one in the Mulberry Contest, involved a frisbee, and easily led her to the next round. Combusken was then used for May's battle against Drew, which started in Thinning the Hoard! and ended in the following episode, Channeling the Battle Zone!. It battled against Drew's Flygon and Absol, alongside Squirtle; however, the fierce battle left only Combusken and Absol on stage after the first half of the five minutes. Just when Absol started to get the advantage, Combusken learned Overheat and gave its very best until the end of the match; by an extremely narrow difference, May and Combusken were announced as the winners of the round, and May moved on to the semi-finals. Combusken then faced Solidad's Pidgeot and Slowbro, battling along with Munchlax. As Solidad had been observing May's battling style, she was able to evade their attacks and defeat them with relative ease, leaving May at the Top 4 of the Grand Festival.
In Once More with Reeling, during the break of a Pokémon Contest, Ash and his friends were trying to stop Team Rocket from stealing Pikachu and other Pokémon. In the midst of the ensuing battle, Combusken evolved into Blaziken, and used its Blaze Kick to send Team Rocket flying, upon which Ash remarked "would I love to battle you". Afterwards, May used Blaziken in the Battle Phase of the unofficial Terracotta Town Pokémon Contest against Ash's Sceptile. Although it had a type advantage over Sceptile and its Blaze Ability activated at the same time Sceptile's Overgrow did, the battle ended in a tie. Later, it left for Johto with May and the rest of her Pokémon.
Blaziken appeared again when May made a guest appearance in A Full Course Tag Battle!. It was used in the Seven Stars Restaurant Tag Battles, in which it battled alongside Dawn's Piplup. When it was first called out, Ash seemed to be pleased at seeing it again, and Brock remarked that it had gotten stronger as well. After the food retrieval from Team Rocket, it was called out once again for the Tag Battle. Blaziken started off with a Blaze Kick but failed to hit the opponent and got hurt by Girafarig's Bite. The battle concluded with a combination of Piplup's Bubble Beam and Blaziken's Fire Spin, resulting in a fusion of the Fire-type and Water-type moves, knocking off both of the opponents as a result. Blaziken was not seen in the Wallace Cup.
Much like May in the beginning of her journey, Torchic was very inexperienced and unsure of itself. It was also shown to be a rather curious, ditzy, and playful Pokémon. It did not know how to battle and it tended to wander around aimlessly when brought out of its Poké Ball. Additionally, it used to panic when in dangerous situations.
When May started to ignore Torchic in favor of her Beautifly, Torchic felt like it needed to compete for May's attention and its personality began to change: it grew more determined to improve itself and recapture May's attention. Its competitive streak continued to grow as it lost most of its childishness and confusion; this culminated in its evolution into Combusken in A Shroomish Skirmish, where it learned both Fire Spin and Sky Uppercut.
Upon its evolution, it became much more assertive and confident, as it felt it didn't need to compete with Beautifly for attention anymore. As a Blaziken it was shown to be quite an adept battler, being able to battle on par with Ash's Sceptile and work well with Dawn's Piplup.