Ash's Pikachu (Aura)

Ash's Pikachu is the first Pokémon obtained by Ash Calem Ketchum on his journey as a Pokémon Trainer.

Personality and characteristics
After Ash gained Pikachu's loyalty, Pikachu became extremely loyal to Ash and has maintained this loyalty, and while he is not always immediately trusting of strangers, he is generally friendly to humans and Pokémon alike. He acted as a guardian and big brother to Serena's Togepi, and has been seen mediating and even breaking up fights among other Pokémon. During the events on New Island, Pikachu, Smaug, Ash's Dratini, and Dratini's clone were the only Pokémon not to participate in the giant battle; Pikachu stood motionless as his clone repeatedly slapped his face. Contrary to his distrusting nature, Pikachu took a liking to Serena very early, and has retained this liking to this day.

On several occasions, Pikachu has developed an "electric flu" causing him to become overcharged and extremely powerful. During these instances, Pikachu will sometimes accidentally let off electric outbursts which can be set off on anyone, including Ash. In all of these cases, Pikachu did not mean harm upon anyone.

Pikachu has a special fondness for ketchup, but he will eat and enjoy almost any other human or Pokémon food.

Pikachu, like his Trainer, is always happy to battle. He often tries his very best, but when he loses, he doesn't complain or feel bad about himself, especially when Ash reassures him. Ash and Pikachu are almost identical personality-wise, and thus are the perfect match for one another.

In general, Pikachu as a species is not particularly powerful, but Ash's Pikachu is an anomaly, overcoming odds in battle numerous times. Jacob McKnight even noted that Pikachu's power "far exceeds his evolutionary level". Ash's Pikachu has also defeated very powerful Pokémon that Ash's other Pokémon were unable to, such as Rhyperior, Metagross, and Mega Lucario. He has helped Ash win countless battles and Gym and League matches.

However, at times, Pikachu has lived up to his species' frail and brittle strengths, particularly in Gym battles where he was defeated with relative ease by his opponent; for example, he was overpowered very easily by Bugsy's Scyther, Whitney's Miltank, Chuck's Poliwrath, Roark's Rampardos, Fantina's Drifblim, and Viola's Surskit, despite having a type advantage with Scyther, Poliwrath, Drifblim, and Surskit. He also drew against Norman's Vigoroth, Winona's Pelipper, Cress' Panpour, and struggled against Crasher Wake's Floatzel.

Even with his high level of electrical power, Pikachu has not stopped learning new attacks. Upon learning that Brock, the Pewter City Gym Leader used Rock types, Ash had Pikachu learn Iron Tail with TM23 given to him by Jacob. This move allowed Pikachu to defeat Brock's Onix and earn Ash his first Kanto Badge. In addition to giving Pikachu an advantage over Rock types, Iron Tail has allowed Pikachu to defeat many powerful opponents. Later on in their journey, Ash ordered Pikachu to do a Quick Attack. Much to the surprise of Ash and his friends, the Quick Attack morphed into Volt Tackle, and he later learned Electro Ball. Not only that, Pikachu has used his ability, Static, a few times in battle.