Cursed
"Your pokemon becomes cursed by a ____'s Curse spell."
(Make Curse a VERY rare attack from Random poke duals) [for instance, you can duel other trainers pokemon, and they use attacks you didn't give.]
luminous
"Your pokemon achieves a point of lumninosity by holding the Luminous Orb."
(Luminous Orb very expensive coin purchase, one time use)
Shadow
"You caught a ___ with a Shadow Ball, Your new pokemon has obtained a dark side and became Shadow ___'
(Shadow ball, Again, VERY expensive)
Rainbow
"You're holding a Rainbow Feather while catching a ___ with a pokeball, your new ___ has gained a Rainbow color"
(Rainbow Wing, Expensive, One time use)
etc. etc.

This idea could actually work, 10/10