I did some further testing on this. I recreated the same battle both in Showdown and on the 3DS, to show the differences between both of them.
Before talking about the replays, I'm gonna share the EV Spread I used, so that we can have a reference when doing the damage calcs:
All of them have 31 IV's on every stat
Aegislash: 244 HP / 0 Def, Modest Nature
Incineroar: 244 HP / 252 Attack, Adamant Nature
Togedemaru: 4 HP / 0 Def, Jolly Nature, Ability: Lightning Rod (not Iron barbs)
Basically this is what going to happen in both of these replays:
- RaahxenPOV (Trainer A) sents out Incineroar and Togedemaru
- SmileyPsyduck (Trainer B) sents out Incineroar and Aegislash
Turn 1:
- RaahxenPOV's Togedemaru uses Spiky Shield
- SmileyPsyduck's Aegislash uses King's Shield
- RaahxenPOV's Incineroar uses Malicious Moonsault (Incineroar's Z-Move that makes Contact) into Aegislash's King's Shield
-> In Pokemon Showdown, RaahxenPOV's Incineroar doesn't get his attack dropped
-> On 3DS Link Battle, RaahxenPOV's Incineroar Attack drops 2 stages
- SmileyPsyduck's Incineroar uses Malicious Moonsault (Incineroar's Z-Move that makes Contact) into Togedemaru's Spiky Shield
-> In Pokemon Showdown, RaahxenPOV's Incineroar doesn't lose any HP
-> On 3DS Link Battle, RaahxenPOV's Incineroar loses 1/8 of his HP (25 HP)
Turn 2:
- SmileyPsyduck's Incineroar Protects
- Togedemaru uses Fake Out (and it fails)
- Aegislash stays in Shield form by using Wide Guard
- SmileyPsyduck's Incineroar uses Darkest Llariat into Aegislash-Shield
-> In Pokemon Showdown, Aegislash gets KOd by a +0 Incineroar Darkest Lariat (it was a damage roll)
252+ Atk Incineroar Darkest Lariat vs. 244 HP / 0 Def Aegislash-Shield: 104-126 (62.6 - 75.9%) -- guaranteed 2HKO
-> On 3DS Link Battle, Aegislash-Shield takes 62 damage from Darkest Lariat (I got a high roll)
-2 252+ Atk Incineroar Darkest Lariat vs. 244 HP / 0 Def Aegislash-Shield: 54-66 (32.5 - 39.7%) -- 98.6% chance to 3HKO
Possible damage rolls (HP number):
(54, 54, 56, 56, 56, 56, 60, 60, 60, 60, 60, 62, 62, 62, 62, 66)
Pokémon Showdown replay:
https://replay.pokemonshowdown.com/gen7vgc2018-695013947
3DS Battle (FQUG-WWWW-WWWF-ZWK5):
As of right now, I don't have a Pokémon with Baneful Bunker to test this with, but I'll try to get one later.
But seeing how this went down, I'd say that Pokémon Showdown doesn't recognize "Z-Moves that make contact" as contact moves.
List of Z-Moves that make contact:
- Let's Snuggle Forever (Mimikium Z, Mimikyu's exclusive Z-Move)
- Malicious Moonsault (Incinium Z, Incineroar's exclusive Z-Move)
- Pulverizing Pancake (Snorlium Z, Snorlax's exclusive Z-Move)
- Searing Sunraze Smash (Solganium Z, Z-Move exclusive to Solgaleo and Dusk Mane Necrozma)
- Soul-Stealing 7-Star Strike (Marshadium Z, Marshadow's exclusive Z-Move)
So I'd say that this applies to every single attack and ability listed under "Effects involving this contact":
https://bulbapedia.bulbagarden.net/wiki/Contact
Here's an image to make thing easier: