When you go to Route 10 before getting the 2nd badge, you can go all the way to Geosenge Town, but your way to Route 11 is blocked. Once you've beaten Grant, Team Flare Grunts appear on Route 10, two of whom are required. You can avoid having to battle these trainers by going to Geosenge Town Pokémon Center before Grant, and intentionally blacking out after having beaten him. Right now I'm thinking the most consistent way to deathwarp would be to battle Swimmer Marisa on Route 8 and dying to her Masquerain.
For a Lv. 20 Hawlucha, I would probably use 2 Rare Candies on it and progress as normal. For a Lv. 19 Hawlucha, there are some trouble points:
- You're Lv. 22 for Lane's Linoone instead of Lv. 23, so +2 Karate Chop is a tough range
- You're Lv. 24 for Franz's Golett instead of Lv. 25, so +2 Wing Attack is a range
- You're Lv. 24 for Calem 1's Meowstic instead of Lv. 25, so you need the X Speed unless you have 62 Speed at Lv. 21 instead of 57 Speed at Lv. 20
- You're Lv. 27 for Dash's Heracross instead of Lv. 28, so Wing Attack is a range and Counter is scary
- You're Lv. 29 for Korrina's Hawlucha instead of Lv. 30, so to guarantee the range you need to X Attack at 71 Attack instead of 64
- You take a bit more damage here and there
- You can get encounters in Reflection Cave before Lane, with a small chance of encounters before Monique
I'll be able to test a little more when I get home. I know these aren't popular speedgames, but hopefully this information will be interesting to some of you.