https://replay.pokemonshowdown.com/gen1randombattle-793592968
On turn 4, my Ditto transformed to copy an Oddish with +2 Attack. On turn 6, its non-crit Double-Edge only did 25.1% damage, which is what it would do if it had no boosts. The stat boost apparently didn't get copied by Transform.
Oddish Double-Edge vs. Oddish: 61-72 (23.9 - 28.2%)
+2 Oddish Double-Edge vs. Oddish: 123-145 (47.4 - 55.9%)
I'm not familiar with the RBY mechanics for Transform so it's possible that boosts really don't get copied (although I can't find any source that says so, and that would directly contradict the PS gen 1 move description that was updated 2 days ago), so I'm not certain if this is a bug in the behavior for ignoring my boosts or a bug in the UI for showing boosts that I don't really have, but either way it's a bug.
On turn 4, my Ditto transformed to copy an Oddish with +2 Attack. On turn 6, its non-crit Double-Edge only did 25.1% damage, which is what it would do if it had no boosts. The stat boost apparently didn't get copied by Transform.
Oddish Double-Edge vs. Oddish: 61-72 (23.9 - 28.2%)
+2 Oddish Double-Edge vs. Oddish: 123-145 (47.4 - 55.9%)
I'm not familiar with the RBY mechanics for Transform so it's possible that boosts really don't get copied (although I can't find any source that says so, and that would directly contradict the PS gen 1 move description that was updated 2 days ago), so I'm not certain if this is a bug in the behavior for ignoring my boosts or a bug in the UI for showing boosts that I don't really have, but either way it's a bug.