Okay, I've been trying to compile correct info about Substitute for the purpose of Shoddy Battle. I figure you guys could help and could use the info either way. I will say from the start that everything here was either tested in RSE and assumed to be the same or gleaned from this or the previous research thread. I'm sorry if this isn't very useful (and glad if it is useful), but this is what I have compiled.
Sandslash, a regular on AAMS, deserves full credit for most of the obscure RSE tests. I don't want to be a credit thief for testing I didn't do!
Substitute takes 25% of the user’s HP, rounded down, to summon a doll to take hits for the Pokemon that used it. This doll has its own HP total, initially equal to the amount of HP consumed to create it, which cannot ever be increased by any means. It blocks all named status effects and effectively has the Clear Body trait. Its defense and special defense are equal to that of the Pokemon which is currently behind it.
Absorb and friends heal HP when hitting subs
Substitute does not block Attract
Multi-hit moves such as Rock Blast will break substitute on the hit that does the fatal damage. Remaining hits will hit the Pokemon that was formerly behind the substitute. This includes Beat Up.
Substitute can be transferred to another Pokemon via Baton Pass. The Substitute keeps its current HP when this happens.
Substitute blocks the effects of partial trapping moves such as Bind. The moves still do their damage from the hit, but they don’t do end of turn damage or prevent switching.
Substitute blocks the effects of full trapping moves such as Mean Look, Block, and Spider Web.
Pokemon with a substitute up cannot be confused by any means. If a Pokemon is already confused when it uses Substitute and then hurts itself in confusion, the Substitute will not take the damage for it.
Damage inflicted to a substitute does not count toward “countering” moves such as Bide or Counter.
Substitute does not block added effects to attacks that benefit the user such as Charge Beam’s special attack boost.
Substitute blocks the effects of Curse when used by a ghost type.
Substitute does not block the effects of Disable.
Substitutes cause Dream Eater to fail. Yes, I know that’s really weird.
Substitutes take damage from Endeavor. For the purpose of Endeavor, the HP of the Pokemon behind the Substitute is used. Whatever damage would be dealt to the Pokemon behind the Substitute is done to the Substitute which may or may not break the Substitute depending on how much damage it is.
Substitute does take the damage from Future Sight and Doom Desire.
Substitutes can be broken by False Swipe.
Substitutes are immune to all forms of flinching.
Substitutes are instantly killed by OHKO moves, but the Pokemon behind them is unharmed.
Substitutes entirely block the effects of Flatter and Swagger, including the stat increases.
This is very well known, but damage dealt to Substitutes does not interrupt Focus Punch.
Since Gravity is a field effect, Substitute does not affect it. Gravity has full effect on Pokemon with Substitutes up.
Substitutes block the effects of Grudge.
Substitutes cause Mimic and Sketch to fail. Presumably, this includes Copycat as well.
Substitutes do not take damage from Hail or Sandstorm. The Pokemon behind the Substitute takes the damage.
Substitutes do not block Haze.
Substitute does not block Imprison.
Knock Off can’t force a Substitute to drop an item.
Substitute blocks the effects of Leech Seed.
Substitute blocks the effects of Lock On and Mind Reader.
A Pokemon under the effects of both Substitute and magic coat can still reflect status effects. In fact, Magic Coat reflects a status inflicting move under all circumstances, regardless of the Magic Coat user’s status immunity.
Substitute blocks the effects of Nightmare.
Substitutes do not block the effects of Foresight, Odor Sleuth, or Miracle Eye.
Substitutes block Pain Split when used by the enemy Pokemon. Pokemon behind Substitutes can use Pain Split against unprotected Pokemon just fine.
Damage dealt to Substitutes does not count toward doubling the power of Revenge, Avalance, or Payback.
Substitutes do not block the effects of Perish Song.
Substitutes do not block the effects of Psych Up
Present’s healing effect will hit a Pokemon behind a Substitute. The Substitute takes the damage if Present chooses to do damage.
Substitutes take the hit from Pursuit.
Substitutes do not block the effects of Rapid Spin.
Substitutes do not block the effects of Roar or Whirlwind.
Damage inflicted to a substitute does not cause Rage to build.
Both Role Play and Skill Swap hit through Substitute
Super Fang deals damage to a substitute equal to the damage it would deal to the user if the substitute were not there.
Substitute can be Snatched.
Substitute does not block Spite.
Substitute blocks the effects of Trick and Switcharoo. The Pokemon behind the Substitute can still use these moves freely.
Smellingsalt and Wake Up Slap cannot cure status effects or do double damage against Substitutes.
Substitute obviously fails when the user already has a Substitute.
Taunt hits through Substitutes in DP mode but not in RSE mode.
The item stealing of Thief and Covet will not happen when used on a Substitute.
Torment hits through Substitutes.
Transform allows the user to transform into the other Pokemon even if the other Pokemon has a Substitute up.
To be clear, Tickle only hits through subs in RSE. It does not hit through Subs in DP.
Substitute does not block the effects of Yawn in DP. It only does so in RSE.
Substitutes that are Baton Passed to another Pokemon do not take the damage from Spikes and Stealth Rock. The Pokemon that is newly behind the Substitute takes the damage.
Substitutes will not take recoil damage from moves like Double-edge or
crashing damage when Hi Jump Kick or Jump Kick miss. The user will take
this damage. If a Pokemon using a recoil move attacks a substitute, the user will take recoil damage.
Attacking a Substitute does not cause a Life Orb to drain the health of the attacker.
The Enigma, Rowap, and Jaboca berries won't activate for a Substitute.
All other items (one possible exception) act on the holder of the items as per normal regardless of Substitute.
All traits act normally when interacting with Substitute. Intimidate is blocked, but all the others behave as though the Substitute weren't there. Water Absorb heals the Pokemon behind the Sub, Flash Fire will boost fire power, Synchronize will still transmit status, Static will still paralyze, etc. As far as traits go, Substitute doesn't exist.
The following moves still need tested for their interaction with Substitute:
Assurance, Embargo, Gastro Acid, Guard Swap, Power Swap, Heart Swap, Heal Block, Mirror Move, Bug Bite, Pluck, Psycho Shift, Worry Seed, Toxic Spikes
Also, the interaction between substitutes and Hooked Spikes needs tested as does the interaction with all of the super-effective berries.