A few more impossible movesets allowed by Pokemon Showdown have cropped up with some of the recent Virtual Console releases. These are mostly routed in future generation exclusive pre evo level up attacks + Evolved Pokemon Gen 1-2 exclusive attacks.
To give an example:
Vaporeon
-Baton Pass - Only Eevee can learn the attack from Crystal-On
-Bubblebeam - Gen 1 Exclusive TM for Vaporeon only
Some impossible movesets can also develop from a combination of three attacks.
Jolteon
-Baton Pass - Only Eevee can learn the attack from Crystal-On
-Flash - Gen 1-3 HM, Gen 4-5 TM only Jolteon can learn.
-Focus Energy - Eevee learns by level up in Yellow, Gold, Silver at level 43, leaves movepool from Crystal-On. Focus Energy is legal with Baton Pass or Flash, but not both. Baton Pass + Flash + HA is legal without Focus Energy.
Other Pokemon effected include Arcanine (Teleport + Any non gen 1 Pre Evo Exclusive attack), Vileplume (HA Body Slam + Any non gen 1 Pre Evo Exclusive attack). Gen 2's Poketransfer update will fix a few of these (HA Body Slam + Sweet Scent Vileplume) but add several more (Zap Cannon + Focus Energy + Baton Pass Flareon, Dynamich Punch + Slack Off Slowking).
Additionally, Bubblebeam + Baton Pass isn't caught by the gen 2 legality checker for a different reason. Since Baton Pass is an Eevee exclusive gen 2 move and Bubblebeam is a Gen 1 TM exclusive, the combo shouldn't be possible.
To give an example:
Vaporeon
-Baton Pass - Only Eevee can learn the attack from Crystal-On
-Bubblebeam - Gen 1 Exclusive TM for Vaporeon only
Some impossible movesets can also develop from a combination of three attacks.
Jolteon
-Baton Pass - Only Eevee can learn the attack from Crystal-On
-Flash - Gen 1-3 HM, Gen 4-5 TM only Jolteon can learn.
-Focus Energy - Eevee learns by level up in Yellow, Gold, Silver at level 43, leaves movepool from Crystal-On. Focus Energy is legal with Baton Pass or Flash, but not both. Baton Pass + Flash + HA is legal without Focus Energy.
Other Pokemon effected include Arcanine (Teleport + Any non gen 1 Pre Evo Exclusive attack), Vileplume (HA Body Slam + Any non gen 1 Pre Evo Exclusive attack). Gen 2's Poketransfer update will fix a few of these (HA Body Slam + Sweet Scent Vileplume) but add several more (Zap Cannon + Focus Energy + Baton Pass Flareon, Dynamich Punch + Slack Off Slowking).
Additionally, Bubblebeam + Baton Pass isn't caught by the gen 2 legality checker for a different reason. Since Baton Pass is an Eevee exclusive gen 2 move and Bubblebeam is a Gen 1 TM exclusive, the combo shouldn't be possible.