This is mostly trivia, but I've always wondered this. And you don't have to include Megas but you can if you want to.
Update: As of Gen 9
Source
Upon evolving,
Upon Mega-Evolving,
And that's it. Edit this answer if I've forgot a Pokemon, Editors and stronger !
Normal evolutions
Azurill - loses Normal type but gains Water type Bellossom - loses Poison type Eevee - changes type upon all 7 evolutions Fletchling - loses Normal type but gains Fire type Kirlia - loses Fairy type but gains Fighting type upon evolving into Gallade Nincada - loses Ground type but gains Flying type as Ninjask and Ghost type as Shedinja Onix - loses Rock type but gains Steel type Pupitar - loses Ground type but gains Dark type Scyther - loses Flying type but gains Steel type Skorupi - loses Bug type but gains Dark type Skrelp - loses Water type but gains Dragon type Surskit - loses Water type but gains Flying type Swablu - loses Normal type but gains Dragon type
Mega evolutions
Aggron - loses Rock type Charizard - loses Flying type but gains Dragon type upon evolving into Mega Charizard X Gyarados - loses Flying type but gains Dark type