What are the pros and cons of delaying these evolutions?

Question

Tyrogue
Feebas
Eevee
Slugma
Wingull
Burmy
Darumaka
Karrablast

Each of them holding Evoilite.
http://pokemondb.net/pokebase/118428/evolved-pokemon-holding-evoilite-better-defense-evolutions

Answer 1

For those Pokemon, all of their evolutions are superior, even if they hold the Eviolite. There will be little to no benefit in keeping them un-evolved.

Answer 2

Delaying evolution usually depends on the moveset the Pokemon will learn.

Eevee can learn Baton Pass at level 33, but none of the Eeveelutions can learn it, so if you want Baton Pass on e.g. an Umbreon, it needs to be Level 33 as an Eevee before you can evolve it.

Tyrogue can only learn 4 moves, so there's no merit in delaying its Evolution. Same with Feebas and Burmy.

Karrablast's moveset differs from Escavaliers, but none of the moves it learns are really something that you'd use/ want.

Darumaka and Slugma have zero benefit from delaying their evolution; they will learn the same moves and more when evolved.

Wingull will learn Quick Attack, Pursuit, Air Cutter and Air Slash after level 25, which is its evolution level for Pelipper. However, they're not moves you really want, since it will learn Hurricane at 63 as a Pelipper, Quick Attack is seldom used at this stage, and get a STAB move in favour of Pursuit.

EDIT: I forgot to say; in regards to Evolite, no there is no merit in delaying their evolution.

Answer 3

There are no pros. The only the occasion you would want to do this is if the Pokemon learns a move that its evolved form does not.