Needs Triage Bug Report - Mechanics

[17 character name]

What type of bug are you reporting? Mechanics

What is the bug?
There is a weird interaction between transforming/imposter and tera. When you send out a pokemon that has terastilized to tera stellar and has the imposter ability imposter won't activate. Transform will always fail if you have terastilized, but imposter only fails to activate if you're tera stellar. I don't know if this happens on cart, I don't have somebody to test this with.

Are you able to replicate it? If so, how?
By sending out a pokemon with imposter, terastilizing to tera stellar then switching out and switching back in again.
Here are replays:

https://replay.pokemonshowdown.com/gen9nationaldexag-2517276612-trdnju10gnbk8unwxr1ynrmn2drmsnvpw

and

https://replay.pokemonshowdown.com/gen9nationaldexag-2517278776-3vyhk436qaj2kkdviqnf6u0tw8apjropw

 

[Hydrametr0nice]

Transform will always fail if you have terastilized

Where? Not on PS.

but imposter only fails to activate if you're tera stellar

Same as Transform.

I don't know if this happens on cart

Yes, you can't transform by any method if you are Terastallized into the Stellar type.