There's actually a few more ways to get Sturdy on Shedinja besides your method. I'll talk about those later, however.
Entrainment + Mimic
This strategy is flawed, as it requires Shedinja to be stuck with Own Tempo / Moody for a turn, making it vunerable to pretty much any attack. So, you would need to use Entrainment on the opponent, have the other Pokemon Mimic the move, then use them on Shedinja the following turn. For this, you'd probably want fast users of both Entrainment and Mimic to get them onto Shedinja asap. However, the problem is, the fastest user of Mimic with Sturdy is Magneton. And because you're facing multiple Pokemon, Sturdy / Focus Sash doesn't necesarily help, as multi targetting is a thing. You're pretty much forced to run Sashes regardless to have any hope of getting the strategy off.
Hawlucha is the fastest user of Entrainment before Mega Lopunny, but Lopunny is slower before mega evolving, and has worse defensive typing. However, the user of Entrainment does not need to be fast, as long as it is faster than the Mimicing Pokemon. However, Hawlucha has the better defensive typing in the long run out of the Entrainment users.
Hawlucha @ Focus Sash
EVs: 4 HP / 252 Atk / 252 Spe
- High Jump Kick
- Thunder Punch
- Iron Head
Shedinja @ Focus Sash
Ability: Wonder Guard
EVs: 252 Atk / 4 Def / 252 Spe
This depends on the type of Shedinja you want. You can run some kind of annoyer set or boosting set.
Magneton @ Eviolite
EVs: 252 SpA / 4 SpD / 252 Spe
IVs: 2 Atk / 30 Def / 30 SpD / 30 Spe
- Flash Cannon
- Hidden Power Fire
Worry Seed / Simple Beam / Gastro Acid + Skill Swap
The goal here is to replace Wonder Guard so it can be Skill Swapped with. The benefit of this is that this can be done in 1 turn, as opposed to 2 turns for the previous ones. The problem with this is that only one Pokemon has Skill Swap + Sturdy - Carbink. It's reasonably bulky, however, which can aide in getting Sturdy over.
Basically, any Pokemon that is faster than uninvested min Speed Carbink and has one of those 3 moves works.
Worry Seed: Abomasnow, Amoonguss, Bayleef, Bellossom, Bellsprout, Breloom, Budew, Bulbasaur, Cacnea, Cacturne, Carnivine, Celebi, Cherrim, Cherubi, Chesnaught, Chespin, Chikorita, Cottonee, Cradily, Deerling, Exeggcute, Exeggutor, Ferroseed, Ferrothorn, Flabebe, Floette, Florges, Foongus, Gloom, Gogoat, Golduck, Gourgeist, Grotle, Grovyle, Hoppip, Ivysaur, Jumpluff, Leafeon, Leavanny, Lileep, Lilligant, Maractus, Meganium, Mew, Munna, Musharna, Nuzleaf, Oddish, Pansage, Paras, Parasect, Petilil, Phantump, Psyduck, Pumpkaboo, Quilladin, Roselia, Roserade, Sawsbuck, Sceptile, Seedot, Serperior, Servine, Sewaddle, Shaymin, Shiftry, Shroomish, Simisage, Skiddo, Skiploom, Smeargle, Snivy, Snover, Sunflora, Sunkern, Swadloon, Tangela, Tangrowth, Torterra, Treecko, Trevenant, Tropius, Turtwig, Venusaur, Victreebel, Vileplume, Virizion, Weepinbell, Whimsicott, Wormadam
Simple Beam: Audino, Beheeyem, Delcatty, Elgyem, Farfetch'd, Genesect, Golduck, Grumpig, Inkay, Linoone, Malamar, Natu, Psyduck, Skitty, Smeargle, Spoink, Xatu, Zigzagoon
Gastro Acid: Accelgor, Amoonguss, Arbok, Bellossom, Bellsprout, Carnivine, Cradily, Diggersby, Eelektrik, Eelektross, Ekans, Foongus, Galvantula, Gloom, Gulpin, Heatmor, Joltik, Lileep, Mew, Oddish, Palpitoad, Panpour, Pansage, Pansear, Seismitoad, Serperior, Servine, Seviper, Shelmet, Shuckle, Simipour, Simisage, Simisear, Slurpuff, Smeargle, Snivy, Swalot, Swirlix, Victreebel, Vileplume, Weepinbell
Carbink @ Sitrus Berry
EVs: 252 HP / 252 Def / 4 SpD
IVs: 0 Spe
- Skill Swap
Rest of the moves are filler. You can use Light Screen, Reflect, Moonblast, Stone Edge, Toxic, Magic Coat, etc.