Venusaur, Crobat and Scolipede: I was a poison gym leader in a pixelmon server 11 years ago.
Slowbro and Slowking: In the same pixelmon server, my first ev trained pokemon was a slowbro called Boo-chan (from Shin Chan)
Breloom and Skarmory: I used them in my first approach to competitive pokemon.
Regarding the rest, I either find them majestic, whimsical or super consistent as designs. There are no designs from 6th gens or above except for Lunala, because the most recent pokemon game I've played is Black 2, but Lunala just looks too good. The best designs, to me, are in the second gen like this anon
>>58424877 says, unless he likes them for other reasons.