Pokémon Crystal Dust Extra EXP Benefits

Below is a summary of the benefits to getting extra EXP in Crystal Dust (incomplete).

All three routes take the right path in Azalea Gym and fight Al, as well as Benny.
No extra EXP route doesn’t fight any additional optionals.
Extra EXP route fights two additional trainers, which ones depend on whether you have Torrent (12 or less HP) after Sprout Tower. Both fight Anthony (Geodude – WG; Machop – WG x 2)

A. [Torrent] Fight Bill (Koffing x 2, each dies to 1 WG)
B. [No Torrent] Fight Daniel (Onix – WG) and one wild encounter yielding 21 or more EXP.

Note: Onix outspeeds Toto and does 3-4 (6-8 with crit) with Tackle (95% acc) and 2-3 (5-6 with crit) plus 2 with Bind (75% acc), so this option is possible in Torrent, albeit riskier, depending on HP. He also knows Screech.

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Well Grunt 1:
100% 2HKO to use Rage + Scratch on Rat 1, without Rage boost (7.03% 2HKO with no extra EXP)
100% OHKO to use Scratch (+1) on Rat 2 (6.25% OHKO with no extra EXP)
66.67% chance to get rage boost (Rat Tackle/QA) and have 3 turn fight
100% OHKO to use WG (Torrent) on Rat 2 (75% OHKO with no extra EXP)

No extra EXP strat is Scratch x 2 both Rats; WG x 1 both in Torrent (second one is 75% range) [2-4 turns]
Save average 0.67 turns if no Torrent

Well Grunt 2:
100% (L16) or 60.94% (L15) 2HKO to use Rage + Scratch/WG on Zubat without Rage boost (0% with no extra EXP)
100% 2HKO to use Scratch x 2 (+1) on Ekans (0% with no extra EXP)
50% to get rage boost (Zubat Leech Life) and 4 turn fight
Torrent strats remain the same (Ekans 2HKO with WG)

No extra EXP strat is Scratch/WG x 2 Zubat and WG x 3 Ekans (if in Torrent, Ekans is a 2HKO) [4-5 turns]
Save average 0.5 turns if no Torrent

Well Grunt 3:
No benefit; can either:
a. Rat: Scratch; Zubat: Scratch x 2; Zubat: Scratch x 2
b. Rat: Rage, Scratch; Zubat: Scratch (+1); Zubat: Scratch (+1) - 66.67% to get rage boost (Rat Tackle/QA) and 4 turn fight
c. Water Gun x 1 all 3 in Torrent

No extra EXP strat is Scratch x 1 Rat and Scratch/WG x 2 both Zubats (if in Torrent, all are OHKOs) [3-5 turns]
Save 0 turns

Well Grunt 4:
No torrent: No benefit, still use WG x 3
Torrent: 2HKO with WG improves to 100% from 99.61%

No extra EXP strat is WG x 3 (x2 if in Torrent) [2-3 turns]
Save 0 turns

Twins:
100% 2HKO to use Rage + Scratch on Ledyba, without Rage boost (82.42% 2HKO with no extra EXP)
25% OHKO to use Scratch (+1) on Spinarak (0% with no extra EXP)
50% to get rage boost (Ledyba Tackle) and 3 turn fight

No extra EXP strat is Scratch x 2 both [4 turns]
Save average 0.5 turns

Al:
Use Rage + WG on Caterpie (100% for no extra and extra EXP)
100% OHKO to use Scratch (+1) on Weedle (56.25% with no extra EXP)

No extra EXP strat is Rage + Scratch Caterpie and Scratch x 1-2 Weedle [3-4 turns]
50% to get 3 turn fight with extra EXP and rage boost
Save average 0.22 turns

Benny:
Weedle: no change
Kakuna: use WG instead of Scratch x 2 (save a turn); Scratch is 43.75% OHKO
Beedrill: use Scratch x 2 instead of Rage x 2 (save Rage text on each hit)

No extra EXP strat is Scratch Weedle, Scratch x 2 Kakuna, and Rage + Scratch Beedrill [5 turns plus rage boosts]
Save 1 turn

Bugsy:
No benefit, though Scyther does less damage per Quick Attack
Possible also to knock Kakuna into heal range with WG. So best to use Scratch + WG on the first two bugs

No extra EXP strat is WG x 2 Kakuna and Metapod; X Att, Leer x 2, Scratch x 2 Scyther
Save 0 turns

Rival 2:
43.75% OHKO to use WG on Gastly (0% with no extra EXP). If miss range, finish with WG
Charging FC once on Gastly puts Bayleef into Overgrow (3HKO), though twice makes Bayleef 2HKO
96.70% 3HKO to use Fury Cutter x 3 on Bayleef if charging starts here (1/4096 range with no extra EXP)
No benefit on Zubat

No extra EXP strat is WG, Fury Cutter x 1-2 on Gastly; Fury Cutter x 2-3 on Bayleef; Scratch x 2 on Zubat [7 turns]
6.56 turns on average (save at least 0.44 turns, doesn't account for Gastly hitting Hypnosis)

Donald: will be L21 and have Bite
100% OHKO with Bite on both Slowpokes
62.5% OHKO with Headbutt on 1st Slowpoke (37.5% OHKO with no extra EXP)
100% OHKO with Headbutt on 2nd Slowpoke (also 100% with no extra EXP)

No extra EXP strat is HB, Scratch on Slowpoke 1; HB, Scratch if Growled on Slowpoke 2 [2-4 turns]
Save 0.375 turns on average, assuming Bite on both Slowpokes with extra EXP and you don't get Yawn/Growl if range is missed on Slowpoke 1 (so likely more turns saved)

Teru:
No benefit

No extra EXP strat is Water Gun the Magnemites and Ice Punch the Voltorb [4 turns]
Save 0 turns

Carrie:
No benefit

No extra EXP strat is Bite, Ice Punch Snubbull [2 turns]
Save 0 turns

Whitney:
100% OHKO with Headbutt at +3 on Clefairy (93.75% OHKO with no extra EXP)
100% 2HKO with Headbutt at +3 on Miltank (97.27% 2HKO with no extra EXP)

No extra EXP strat is X Speed, X Attack x 3, HB Clefairy; HB x 2 Miltank [7 turns if hit ranges]
Negligible turns saved

Kimono Girls:
No benefit (I fight them from right to left and Espeon is a speed tie with no extra EXP strats - with extra EXP I believe Espeon is outsped by Croc)

Save (maybe) half a turn?

Rival 3:
No benefit (if get 46+ extra wild EXP, will be L26 for Bayleef)

Jeffrey
Haunter becomes a 50% range from a 37.5% range with Surf

Connie (Lighthouse)
You get Gatr before this fight, and Marill goes from being an assured 2HKO to a 93.75% range with Headbutt (100% with Strength)
Save 1 turn

TOTAL turns saved: 4.7+
Extra turns (Wild/Daniel or Bill + Anthony) = 5 turns
Might be faster, though if you have Torrent for the well some turns saved are moot (1.17)
Also depends on what Gastly does (only 1/3 to use Hypnosis and 60% to hit it)