I would say kyogre or metagross
My favorite is machamp
(Have no 100iv)
Then it’s more like ‘Missingall’
Rare is only really relative to the area you play in to a degree.
What I might consider rare others around the world might get plenty of and have multiple 100’s.
Apart from the migrating nest I have near home now, Qwilfish aren’t very common for me so I consider my 100% Qwilfish rare.
My rarest: I caught a wild 100IV Bagon without using any trackers.
I’ve also hatched a perfect Snorlax.
One day I leveled up to 37, caught a perfect Rayquaza and hatched a perfect Ralts.
A stupid Chimecho…
As 100iv it can get above cp2000
I don’t even have Chimecho
I had luck and hatched one
If I would invest hundreds of candy that I dont even have
I got 200 chimeco candy I hatched 4 in double candy and 1 outside and great Tom around 30 candy each including 98 iv
100iv front venasor golem, numel now being evolved Tom Pokédex camurupt level 31 now levelled up yes