choose one of the following to have in real life

>Victini
+follows you around constantly granting super-powers
-you never see it and it has no emotional attachment to you

>Manaphy
+heart swaps you with anybody of your choice
-manaphy will leave forever once it happens, so you'll never be swapped back

>Jirachi
+grants infinite wishes
-openly despises you and will ignore some wishes if they sound stupid or OP

>Celebi
+time travel and distortion (slowing it down, reversing it, speeding it up, etc.)
-secretly hates you and will leave you in the dark ages if you piss it off

>Mew
+kawaii motherfucker that enjoys every second with you
-no specific powers, so it's essentially a telepathic cat