Well, to answer your question, Jumpstart cards can be used in the Commander, Legacy, and Vintage formats
While this is already a significant jump, prices quickly increase beyond this point, so this spike might not be done yet
Whats your prettiest card
It can quickly be evolved, and its Heart Stamp attack only costs two energy cards, so if you have it sat on the bench, it can quickly be brought in and knock out a lot of bases Pokmon in one hit
Here are the cards theyve illustrated so far for those curious: PkmnCards @kuroimori PkmnCards Suicune Prismatic Evolutions (PRE) #024 Leafeon Prismatic Evolutions (PRE) #005 Milotic ex Surging Sparks (SSP) #237 Feebas Surging Sparks (SSP) #198 Jirachi Stellar Crown (SCR) #098 Sylveon Shrouded Fable (SFA) #022 Leafeon