As you requested, this list is only for Generation 6 Pokemon games, some of the Pokemon may be catchable in Premier Balls in other games, but not Gen 6.
Tyrunt
Tyrantrum
Amura
Treecko
Grovyle
Sceptile
Torchic
Combusken
Blaziken
Mudkip
Marshtomp
Swampert
Cosplay Pikachu
Chikorita
Bayleef
Meganium
Cyndaquil
Quilava
Typhlosion
Totodile
Croconaw
Feraligatr
Snivy
Servine
Serperior
Tepig
Pignite
Emboar
Oshawott
Dewott
Samurott
Turtwig
Grotle
Torterra
Chimchar
Monferno
Infernape
Piplup
Prinplup
Empoleon
Mew
Kabuto
Kabutops
Omanyte
Omastar
Celebi
Jirachi
Phione
Manaphy
Darkrai
Shaymin
Arceus
Victini
Keldeo
Meloetta
Genesect
Diancie
Hoopa
Volcanion
Beldum
Lileep
Cradily
Aniroth
Armadlo
Cranidos
Rampardos
Sheildon
Bastiodon
Tirtouga
Carracosta
Archen
Archeops
By Breeding
Some Pokemon will only be able to be obtained in a Premier Ball by breeding, they are listed below.
Wynaut
Bulbasaur
Charmander
Squirtle
Chespin
Fennekin
Froakie
Pichu
Cleffa
Igglybuff
Venonat
Meowth
Gastly
Munchlax
Natu
Bonsly
Pineco
Swinub
Kricketot
Shinx
Buizel
Cherubi
Patrat
Purrlion
Blitzel
Drilbur
Darumaka
Yamask
Note: To get all Pokemon in a Premier Ball (That are possible to get in a Premeir Ball) you must have all Gen 6 Pokemon games.
Hope this helps!