A+:
Ferroseed -> Ferrothorn
Pineco -> Forretress
Drilbur -> Excadrill
Cottonee -> Whimsicott

A:
Pawniard -> Bisharp
Bronzor -> Bronzong
Swinub -> Mamoswine
Hippopotas -> Hippowdon

A-:
Cleffa -> Clefable
Larvitar -> Tyranitar
Gible -> Garchomp
Gastly -> Gengar
Abra -> Alakazam
Venipede -> Scolipede

B+:
Foongus -> Amoonguss
Magnemite -> Magnezone
Carvanha -> Sharpedo
Phanpy -> Donphan

B:
Diglett -> Dugtrio
Dwebble -> Crustle
Wooper -> Quagsire
Staryu -> Starmie
Chimchar -> Infernape
Purrloin -> Liepard

B-:
Vullaby -> Mandibuzz
Slowpoke -> Slowbro
Tentacool -> Tentacruel
Fletchling -> Talonflame
Kabuto -> Kabutops
Omanyte -> Omastar
Tirtouga -> Carracosta
Shellder -> Cloyster
Riolu -> Lucario

C+:
Piplup -> Empoleon
Tyrunt -> Tyrantrum
Vulpix -> Ninetales
Bunnelby -> Diggersby
Shroomish -> Breloom
Munchlax -> Snorlax

C:
Tepig -> Emboar
Archen -> Archeops
Frillish -> Jellicent
Porygon -> Porygon2/Z
Chespin -> Chesnaught
Snivy -> Serperior
Bulbasaur -> Venusaur
Happiny -> Chansey

C-:
Cranidos -> Rampardos
Binacle -> Barbaracle
Rhyhorn -> Rhyperior
Mienfoo -> Mienshao
Amaura -> Aurorous
Clamperl -> Gorebyss
Solosis -> Reuniclus
Nosepass -> Probopass
Azurill -> Azumarill

D and below:
Treecko -> Sceptile
Mudkip -> Swampert
Surskit -> Masquerain
Starly -> Staraptor
Eevee -> Eeveelution