Wade appears at first on TV, during a battle between him and Electra, the Gym Leader of Rustbolt City, in the Rikoto League Village, shown at the very beginning of the game. This cutscene is not shown in the current version, however.
After this, he appears when you arrive in Waytide City and will also meet your rivals. He's surprised the player already has 5 Gym Badges, and introduces the player and Rodney to Misty, a Gym Leader from Kanto, and says he will challenge you when you obtain 7 Gym Badges.
After this, he appears as the leader of Waytide City's Gym. This gym is the eighth and final one to be challenged by the player. Trainers who defeat Wade will receive the Torrent Badge, along with TM110 Ripple Wave, and will also be granted access to the Victory Isle.
''What?! (Player's name)? Is that you? It is! Look at you, on your very own Pokémon journey! Mom and Dad actually let you out! Haha! ...Competing in Gym battles? Thats awesome! What?! You already have 5 Gym Badges! You must be doing awesome!''
''Oh, Misty. Yeah, right. (Player's name), this is Misty. She's also a Water-type Gym Leader. She's from the Kanto Region. She's here for the Pokémon Fishing Contest!''
''Hmmm... I had an idea! Misty! You should battle (player's name) so I can see the battling style!''
''That was a good battle! Its good to see how far you've come! I know! How about this! When you have won 7 Badges, I will battle you! What a great way to have a battle! Trying to win your 8th Gym Badge! Sounds good?... Awesome! Now, I have to do some business with our aquarium... How about watching the Fishing Contest with Misty?''
''Yes. I don't see how these teams plans will work. I mean, all 5 stones need to be together for it to work and, if they're all separated, it won't work.''
''Oh. Professor. Wasn't there something you wanted to give these three?''
''Right, guys. You know how it goes for this Gym battle. Once all three of you have 7 Badges, I will battle you but, for now, I gotta get back to the Gym! See ya, guys!''
Wade's sprite from SLLD
Wade's VS sprite from SLLD
Wade's overworld sprite from SLLD
Wade is one of the Water-type Gym Leaders that is the 8th and final Gym in a Region. The others are Wallace in Ruby and Sapphire, Juan in Emerald and Marlon in Black and White Versions 2.
In an old version of one of Wade's quotes, he used to mention Regiearth, Regicore, Regisea, Regiwind and Regivolt, but it was changed, since those 5 Regi Pokémon were scrapped in favor of 5 different Pokémon.