A large crowd has gathered in the stands and the participating Trainers are in gondolas as the Whirl Cup tournament's opening ceremony begins. The announcer explains the history of the event and brings everyone's attention to the Sea Priestess, Maya. She greets the contestants and wishes them good luck. Maya shines her Great Sea Spirit Sapphire towards the sun, and Team Rocket who are working as food vendors, spots their next target to steal. Maya evokes the Sea Spirit Union, and a blue light washes over the entire stadium complex to bring forth the energy of all Water Pokémon. The announcer declares that the prize given to the crowned Alpha Omega will be a Mystic Water pendant.
In the lead-up to the tournament, Ash and Misty get into a heated argument over who will win. Brock cools down the argument and then reminds Ash that he only has one Water Pokémon, so Ash calls Professor Oak from the Pokémon Center. At Oak’s suggestion, Ash sends through his Bayleef and receives Kingler. Back at Professor Oak's Laboratory, Oak calls out Bayleef, but Bayleef's obsession with being with Ash causes her to go into a panic, and she eventually rams into Oak.
The sixth match of the first round pits Ash against Christopher. Ash uses Totodile for this round and his opponent calls out a Kingdra from its Lure Ball. Ash scans Kingdra with his Pokédex and is pleased to see a tough opponent. However, Brock, who is in the bleachers, comments that Ash might not have a good time with this one because it's a dual Water and Dragon-type, making Totodile's Water attacks practically useless. Ash takes the lead and commands Totodile to dive under the water, but Kingdra counters with a Twister. Christopher orders Kingdra to stop the Twister causing Totodile to freefall. Kingdra aims a Water Gun blast, but Totodile lands on one of the platforms. Christopher decides that a Hydro Pump attack is in order, but Totodile dodges the attack and gets close enough to Headbutt the Dragon Pokémon. Kingdra dives to evade and Totodile does the same. Kingdra releases a Smokescreen to cloud the water. With no other option, Ash tells Totodile to jump out of the water. The battle comes to a standstill as Ash anticipates Kingdra's next move. Totodile begins to dance around, and Ash takes that as a sign that everything will be fine. Fed up, Christopher has Kingdra resurface and try another Hydro Pump attack. However, Totodile Bites onto Kingdra's snout, effectively stopping the Hydro Pump. With Kingdra being unable to release the water, it swells to enormous proportions as a result. After a while, Totodile releases his jaw and Kingdra goes flying across the stadium. It hits the water field hard and floats to the surface, knocked out. Ash wins the match and can advance to the next round. After the match, Team Rocket is still devising a plan to get Maya's staff, but they are interrupted when another staff member tells them that there are more hungry customers to serve.
Overnight, Misty stares at the Colosseum from her Pokémon Center room window. Ash offers her some reassurance, and Misty declares that she is simply excited about the upcoming match. Day two of the Whirl Cup begins, and Misty goes up against Harrison in the ninth match. Harrison is one of the older Trainers, so he has a snobbish attitude when he steps up to the arena. The match is on, Corsola against Qwilfish. Qwilfish begins the match by shooting a Water Gun, but Corsola reflects it back with a Mirror Coat. Seeing that this tactic won't work, Harrison orders Quilfish to start swallowing water. As the announcer says that this is used for preparing a volley of spikes, Misty thinks fast. Qwilfish soon releases a Pin Missile barrage and so Corsola counters with Spike Cannon. The two attacks explode in mid-air knocking Corsola back, but Qwilfish took refuge in the waters. Taking advantage of this, Qwilfish strikes Corsola with a Take Down attack. Worried that Corsola is going to burn out anytime, Misty tells it to use Recover, but Qwilfish has already prepared to use Take Down again. By the time Corsola has recovered its stamina, Qwilfish's attack hits. Corsola and Qwilfish dip into the water, but the pair resurface and Quilfish is revealed to be stuck in Corsola’s crown of horns. Misty finally gets an idea and tells Corsola to use Spike Cannon. Corsola fires a close-range Spike Cannon blast which sends Qwilfish sky-high, and Misty wins the match. During the battle, Team Rocket makes their move toward Maya's staff, but Officer Jenny orders them to leave the restricted area, which foils their attempt.
Back at the Pokémon Center, Ash and Misty congratulate each other on making it to the second round. A large commotion alerts the group to the screen featuring the matchups for tomorrow's second-round battles. It turns out that Ash is up against Misty for the next round, and the two friends stare at each other in shock.