After beating Roxanne, we had to go through Route 116 to save Peeko from a Team Aqua grunt, as well as some goods. I found the grunt there, and Dustox managed to beat him despite him using Sand-Attack. I got the Devon Goods back, and returned them to the Devon Corporation, and after some talk I got the BuzzNav. Then, May was waiting for me outside for some reason, but after some insignificant stuff I made my way to Briney's house on Route 104. He got us to Dewford Town. I got the Old Rod from a Fisherman there, and managed to catch a Tentacool that I would name Whiplash. Afterwards I caught a Zubat in the Granite Cave that I once again forgot to nickname right away. I beat the Fishermen on the route, and went back to near Rustboro City to train my team some. I was trying to avoid using Dustox as much as possible, since he was a hair away from Brawly's highest level thanks to him being my only team member for a while.
Eventually, we got their levels up, and they had proper attacking moves, so we were set for the Gym. The trainers weren't much worth discussion, and Brawly I didn't take any damage from either. Zubat 2HKO'd both his team members with Wing Attack.
Afterwards we were able to go to Route 109, but before doing anything else, there were two Pokémon I wanted to get my hands on, so I went through Slateport City. But before going to Route 110, the first thing I did was go to the Name Rater and nickname the two Pokémon I forgot to do so earlier - naming Dustox Larvae and Zubat Fastball. I then went right up to Route 110. The first Pokémon I caught was a Gulpin named Creme Brule. The second was an Oddish named Tiny. The former I'm sure will be a long-term team member, but not the latter, as I have a better Grass-type coming in due time, although this one will be good for Sweet Scent later, at least.
But we went back to beat the trainers. Some of them did a bit of damage, but not much overall. I checked out Slateport City, met with someone at the dock, and entered the museum where I beat some grunts, including the 27th strongest member of Team Aqua. That is oddly specific. Archie then went on about how the world needs more water. Dude, cool it before I give you a 7.8/10. Then there was the brief bit with Lisia at the Contest Hall, but I progressed through Route 109. After an annoying Poké Fan with Plusle and Minun, I wasted no time in getting to May. Zubat couldn't do more than half to her Shroomish, but that was handled with ease. Then her Marshtomp was a thing, but Whiplash managed to poison it with Poison Sting then it was basically just stalling her out. Slugma was taken care of with Whiplash as well.
After she gave me the Dowsing Machine, I went straight to Mauville City, and to Route 117, where I caught a Roselia named Sour Patch and immediately added it to the team. Then I went back to Route 109 and battled the trainers there, as well as on Route 103. Again, there were a few annoying things (like the double battle with Plusle and Minun), but we got through them and got some good EXP. I also bought Venoshock at Mauville City before I went there.
Then I beat Wally in front of the Gym, and decided to enter. The first trainer had a Magnemite that was slightly cumbersome to deal with, but not awful. We did have to deal with a Meditite that knew Thunder Punch, though, and that kind of ripped a hole through my team. But we beat it. Afterwards, it was Gym Leader time!
I began with Sour Patch against Magnemite. I used Magical Leaf, and despite resistance, it did roughly 1/3 even with the Miracle Seed, and he used Thunder Wave and paralyzed me. I switched out for Tiny, which is good since Sour Patch has Natural Cure, as he used Tackle for 1/7 my health. Then came a Thunder Wave, however, but I hit with Sleep Powder. I went back to Sour Patch as he snoozed, and used Magical Leaf, but it got him into the red, and he woke up first turn. REALLY?!?! He paralyzed me with Thunder Wave. I switched out for Tiny again before he healed. He used Tackle again, and I hit once more with Sleep Powder. I went back to Sour Patch as he snoozed, and used Magical Leaf for less than half, and HE WOKE UP ON THE FIRST TURN AGAIN AND USED FRICKEN THUNDER WAVE AGAIN!!!!!!!!! OH MY GOD!!!!!!!!!! STOP WAKING UP SO I CAN FINISH YOU OFF!!!!!!!!!! I had to switch to Tiny AGAIN, take another Tackle (but still have over half my health left), and then he used Volt Switch for a bit under half my remaining health, but I had an Oran Berry. And then he came to Magneton.
But that was immediately met with a Sleep Powder. I switched to Larvae, and he was faster but continued to snooze, while I hit with a Struggle Bug for a very weak hit but lowering his Sp Atk. Same deal next turn. Then he woke up and used Supersonic, which sadly hit, and I hit myself. Knowing that staying in was pointless, I brought in Whiplash, as he used Magnet Bomb for 1/3 my health. Ouch! He hit with Supersonic again, but I hit through confusion, and Water Pulse got him to half and confused him, too. But he hit through it and used Volt Switch, and even with -2 I barely lived, and Voltorb came in.
And I hit myself in confusion and was KO'd. I brought in Sour Patch and took a very weak Volt Switch, as he went to Magneton again. Magical Leaf did over half his remaining health, leaving him in KO range of another, but he used Supersonic again. Afraid to stay in, I brought in Creme Brule, and he used Magnet Bomb for less than 1/5 my health. He missed with Supersonic - mercifully so - as I used Yawn. I stayed in on the off-chance that he would hit with Supersonic - which he did - after a pointless Quick Claw before getting Yawn, though. Then he fell asleep. I brought in Sour Patch again as he snoozed… And he didn't wake up next turn! That allowed me to finish him with Magical Leaf. Sour Patch, Tiny and Creme Brule all gained levels, too.
Magnemite was next up again, and Magical Leaf got it super close to finishing it off, but he used Thunder Wave. I brought in Fastball as he used Tackle for a small hit. Bite finished him off.
Last up was Voltorb again, who hadn't done much. I brought in Creme Brule, took a Volt Switch for 1/3 my remaining health, then another, and I used Yawn. Then I switched out for Larvae, took a Volt Switch for 1/5 my health, then he fell asleep. As he snoozed, I used Struggle Bug, which didn't do that much, but it lowered his Sp Atk. Two hits had him below half. He woke up after two turns but didn't do much at all, and two more turns finished him, even after he used Charge on the last turn. Not sure why you didn't do that in the first place…
And with that, I got the Dynamo Badge and a TM I won't be able to use. Heading outside, I saw that Team Aqua were getting ready for their departure...