Ace Emerald vs Burning Sapphire
I actually had a really similar idea the other day, so our game is pretty different. I will be facing my brother (Burning Sapphire) irl. I divided the map into 6 areas, and in each area we will face off using only Pokemon caught (not received) in the area leveled to an agreed level. Post Elite Four, we'll battle once more anything goes.
I'm a very competitive player, and while I'll always play through the game, I don't do nearly as much as my brother. He's done countless different challenges on different games. So we figured this was pretty middle of the road: a semi-competitive challenge run.
My brother's team
My team had a little bit of planning. In Area 1, nothing resists Flying and a lot is weak to it, so Tailow was a must. Ralts came in because it's a little bit stronger than other beginning Pokemon, has a relatively high STAB (50 in confusion), and I figured my brother might have Dustox. Dustox is one of two fully evolved Pokemon by our level cap (10), so I figured it'd be useful.
It's not super complex, so I'll just summarize.
I start Tailow, bro starts Poochyena.
I switch to Dustox to save Tailow for sweeping late game, bro Howls.
Bro Howls again, while I poison with Poison Sting.
Tackle from Poochyena still was pretty terrible, and a tackle fest left Dustox at low health and Poochyena out.
Bro sends out Dustox, like an idiot I forget I have Confusion, tackle for a little while he KO's with Confusion.
I send out Ralts, and end Dustox with about 33% health.
Bro sends out Wingull, who finishes Ralts with about 65% health.
Tailow's Quick Attack did much more than Water Gun, and he cinched the victory.
Ace Emerald: 1
Burning Sapphire: 0
It was pretty close, and we're both looking forward to Area 2.