Wally is the primary rival to the protagonist in Pokemon Ruby/Sapphire. His status of him as the professional Pokemon Trainer is unknown to the player as to how he surmised to producing a strong team up until the last battle of Victory Road where he explains his travels were the enlightening epitome of growth and experience to the world around him.
Wally is the one showing the player how to catch a Pokémon in the third generation games. He borrows a Zigzagoon from the players father Norman, the fifth fym leader.
During the tutorial Wally catches a Ralts which he then keeps as his own and starts his own Pokémon journey, thus becoming the players second rival. (The other being Brendan or May)
Wally presides with his uncle in Petalburgh City. He suffers from a grave undisclosed illness that presents itself as crippling. Even this cannot prevent the young trainer to fulfill his wishes to become a Pokemon Trainer to teach and raise his own Pokemon team.
The protagonist does not know of this character until the father presents to them Wally.
In Pokémon Ruby, Sapphire, and Emerald he is first encounted by the protagonist at the Petalburg City gym directing his concerns to the Gym Leader Norman. Norman goes on to lend Wally a Zigzagoon asking for the advice from the protagonist to catch a wild Pokémon in the near vicinity.
Wally known Pokémon team is built with the reinforcement of Altaria, Delcatty, Magneton, Gardevoir, and Roselia.
The player will battle Wally six times throughout the game, five of those battles takes place on only one place, the Victory Road. After the last battle with him in Victory Road he will remain there for the player to battle him whenever possible. Between the battles until the last his Pokémon will rise in level, as shown below.
This battle takes place in Mauville City. In this fight Wally will use only one Pokémon, a Ralts on lvl. 16.
This is the first of few battles with him in Victory Road. His Pokémon at this point are an Altaria on lvl. 44, a Delcatty on lvl. 43, a Roselia on lvl. 44, a Magneton on lvl. 41 and a Gardevoir on lvl 45.
His Pokémon has gained a few levels this time and will do so until the fifth time. At this point Altaria is lvl. 47, Delcatty on lvl. 46, Roselia on lvl. 47, Magneton on lvl. 44 and Gardevoir on lvl. 48.
At this point Altaria is lvl. 50, Delcatty on lvl. 49, Roselia on lvl. 50, Magneton on lvl. 47 and Gardevoir on lvl. 51.
At this point Altaria is lvl. 53, Delcatty on lvl. 52, Roselia on lvl. 53, Magneton on lvl. 50 and Gardevoir on lvl. 54.
The last battle in which his Pokémon gains levels. After this one they will stay on the level they are. After the last leveling Altaria is lvl. 56, Delcatty on lvl. 55, Roselia on lvl. 56, Magneton on lvl. 53 and Gardevoir on lvl. 57.
We let it all hang out.
The 1st Pokémon I caught.
Pokémon and I have grown stronger together.
Wally is present as friend and is a personal acquaintance in training to Ruby. Wally was assisted by Ruby and was guided enough to catch a Pokemon with Ruby's Ralts as a temporary measure to continue in training to catch another wild Pokémon.
Wally is a holder of the Hoenn Pokédex.
Wally, in his ventures beyond the sage help of Ruby, presides as a pupil to Norman. With this guidance, Wally is situated at the Sky Pillar to awaken the true power within Rayquaza.
Without the Green Orb's assistance, the the threat of unleashing Rayquaza is of great risk for the sake of the good of the world. With concentration, Wally was capable of obtaining Rayquaza and completed the task of what Norman requested of him.