Information from Git repository as of today.
I was going to do railway equipment here as well, but there are over 1,900 introduction and retirement dates for over 1,400 pieces of rolling stock! So here are just the trams.
Trams
1860-08: Introduce vehicle Medium-2-Deck-Trailer (speed 16, capacity 40)
1860-08: Introduce vehicle Tram-Horses (speed 10)
1860-08: Introduce vehicle tram-horse-single (speed 10)
1875-09: Introduce vehicle merryweather-standard-1 (speed 14)
1877-03: Introduce vehicle Medium-large-2-Deck-Trailer (speed 16, capacity 54)
1878-04: Introduce vehicle Steam-Tram (speed 32, capacity 36)
1879-06: Introduce vehicle kitson-standard-1 (speed 16)
1879-12: Introduce vehicle merryweather-standard-2 (speed 14)
1880-02: Retire vehicle merryweather-standard-1 (speed 14, introduced 1875)
1881-01: Introduce vehicle wilkinson-engine (speed 16)
1882-11: Introduce vehicle kitson-standard-2 (speed 16)
1883-01: Retire vehicle kitson-standard-1 (speed 16, introduced 1879)
1883-04: Introduce vehicle Large-2-Deck-Trailer (speed 16, capacity 62)
1885-09: Introduce vehicle Blackpool-Original (speed 30, capacity 55)
1886-05: Introduce vehicle kitson-standard-3 (speed 16)
1887-08: Retire vehicle wilkinson-engine (speed 16, introduced 1881)
1889-02: Retire vehicle Medium-large-2-Deck-Trailer (speed 16, capacity 54, introduced 1877)
1889-05: Introduce vehicle Extra-large-2-Deck-Trailer (speed 16, capacity 74)
1890-04: Introduce vehicle Toastrack (speed 32, capacity 40)
1890-05: Retire vehicle merryweather-standard-2 (speed 14, introduced 1879)
1891-03: Retire vehicle kitson-standard-2 (speed 16, introduced 1882)
1894-10: Retire vehicle Blackpool-Original (speed 30, capacity 55, introduced 1885)
1895-06: Introduce vehicle Blackpool-Dreadnought (speed 32, capacity 65)
1896-07: Retire vehicle Medium-2-Deck-Trailer (speed 16, capacity 40, introduced 1860)
1899-10: Introduce vehicle 1-Deck-Closed (speed 32, capacity 28)
1899-10: Introduce vehicle 2-Deck-Open (speed 32, capacity 51)
1900-03: Retire vehicle Toastrack (speed 32, capacity 40, introduced 1890)
1900-05: Retire vehicle Blackpool-Dreadnought (speed 32, capacity 65, introduced 1895)
1901-06: Introduce vehicle lut-type-z (speed 32, capacity 69)
1902-03: Retire vehicle Large-2-Deck-Trailer (speed 16, capacity 62, introduced 1883)
1902-03: Retire vehicle Steam-Tram (speed 32, capacity 36, introduced 1878)
1903-09: Introduce vehicle lcc-a-class (speed 32, capacity 66)
1903-10: Introduce vehicle lcc-c-class (speed 32, capacity 56)
1904-02: Introduce vehicle 2-Deck-Closed (speed 50, capacity 85)
1906-01: Introduce vehicle lcc-e-class (speed 32, capacity 76)
1906-03: Introduce vehicle lut-type-t (speed 32, capacity 74)
1906-05: Introduce vehicle lcc-g-class (speed 32, capacity 35)
1906-07: Retire vehicle lcc-a-class (speed 32, capacity 66, introduced 1903)
1906-07: Retire vehicle lut-type-z (speed 32, capacity 69, introduced 1901)
1907-04: Retire vehicle 1-Deck-Closed (speed 32, capacity 28, introduced 1899)
1907-07: Retire vehicle Extra-large-2-Deck-Trailer (speed 16, capacity 74, introduced 1889)
1907-08: Introduce vehicle lcc-e1-class (speed 32, capacity 78)
1907-08: Introduce vehicle sheffield-preston (speed 32, capacity 58)
1908-02: Retire vehicle lcc-e-class (speed 32, capacity 76, introduced 1906)
1908-04: Retire vehicle kitson-standard-3 (speed 16, introduced 1886)
1909-02: Retire vehicle lcc-c-class (speed 32, capacity 56, introduced 1903)
1910-08: Introduce vehicle lcc-m-class (speed 32, capacity 62)
1918-01: Retire vehicle Tram-Horses (speed 10, introduced 1860)
1918-01: Retire vehicle tram-horse-single (speed 10, introduced 1860)
1918-12: Introduce vehicle sheffield-rocker-panel (speed 32, capacity 76)
1919-05: Retire vehicle sheffield-preston (speed 32, capacity 58, introduced 1907)
1920-02: Retire vehicle 2-Deck-Open (speed 32, capacity 51, introduced 1899)
1923-08: Introduce vehicle Blackpool-Standard (speed 32, capacity 78)
1923-09: Retire vehicle 2-Deck-Closed (speed 50, capacity 85, introduced 1904)
1927-06: Introduce vehicle sheffield-standard (speed 32, capacity 61)
1929-09: Retire vehicle sheffield-rocker-panel (speed 32, capacity 76, introduced 1918)
1930-09: Introduce vehicle lcc-e3-class (speed 32, capacity 74)
1930-12: Introduce vehicle lcc-hr2-class (speed 32, capacity 74)
1931-11: Retire vehicle lcc-e1-class (speed 32, capacity 78, introduced 1907)
1931-11: Retire vehicle lut-type-t (speed 32, capacity 74, introduced 1906)
1931-12: Retire vehicle lcc-m-class (speed 32, capacity 62, introduced 1910)
1934-04: Introduce vehicle Blackpool-Brush (speed 65, capacity 48)
1934-12: Introduce vehicle Blackpool-Balloon (speed 65, capacity 94)
1936-01: Retire vehicle Blackpool-Standard (speed 32, capacity 78, introduced 1923)
1938-10: Retire vehicle lcc-g-class (speed 32, capacity 35, introduced 1906)
1939-09: Retire vehicle sheffield-standard (speed 32, capacity 61, introduced 1927)
1950-01: Introduce vehicle Sheffield-Roberts (speed 70, capacity 56)
1951-02: Retire vehicle lcc-e3-class (speed 32, capacity 74, introduced 1930)
1951-02: Retire vehicle lcc-hr2-class (speed 32, capacity 74, introduced 1930)
1953-06: Introduce vehicle Blackpool-Coronation (speed 75, capacity 60)
1953-06: Retire vehicle Blackpool-Brush (speed 65, capacity 48, introduced 1934)
1957-05: Retire vehicle Blackpool-Balloon (speed 65, capacity 94, introduced 1934)
1958-03: Introduce vehicle Blackpool-ProgressTwin-Power (speed 70, capacity 53)
1958-03: Introduce vehicle Blackpool-ProgressTwin-Trailer (speed 70, capacity 61)
1958-05: Retire vehicle Blackpool-Coronation (speed 75, capacity 60, introduced 1953)
1962-11: Retire vehicle Sheffield-Roberts (speed 70, capacity 56, introduced 1950)
1967-08: Retire vehicle Blackpool-ProgressTwin-Power (speed 70, capacity 53, introduced 1958)
1967-08: Retire vehicle Blackpool-ProgressTwin-Trailer (speed 70, capacity 61, introduced 1958)
1979-04: Introduce vehicle Blackpool-Jubilee (speed 70, capacity 94)
1984-01: Introduce vehicle Blackpool-Centenary (speed 70, capacity 36)
1992-01: Introduce vehicle Metrolink-T86(Front) (speed 80, capacity 41)
1992-01: Introduce vehicle Metrolink-T86(Rear) (speed 80, capacity 41)
1993-09: Retire vehicle Blackpool-Jubilee (speed 70, capacity 94, introduced 1979)
1994-04: Introduce vehicle Sheffield-Supertram(Front) (speed 80, capacity 32)
1994-04: Introduce vehicle Sheffield-Supertram(Middle) (speed 80, capacity 24)
1994-04: Introduce vehicle Sheffield-Supertram(Rear) (speed 80, capacity 32)
2000-08: Retire vehicle Metrolink-T86(Front) (speed 80, capacity 41, introduced 1992)
2000-08: Retire vehicle Metrolink-T86(Rear) (speed 80, capacity 41, introduced 1992)
2002-02: Introduce vehicle Blackpool-Millenium (speed 70, capacity 94)
2004-03: Introduce vehicle NET-Bombardier-Incentro(Front) (speed 80, capacity 58)
2004-03: Introduce vehicle NET-Bombardier-Incentro(Rear) (speed 80, capacity 58)
2005-10: Retire vehicle Sheffield-Supertram(Front) (speed 80, capacity 32, introduced 1994)
2005-10: Retire vehicle Sheffield-Supertram(Middle) (speed 80, capacity 24, introduced 1994)
2005-10: Retire vehicle Sheffield-Supertram(Rear) (speed 80, capacity 32, introduced 1994)
2005-12: Retire vehicle Blackpool-Millenium (speed 70, capacity 94, introduced 2002)
2015-01: Retire vehicle Blackpool-Centenary (speed 70, capacity 36, introduced 1984)
Gosh - that's a lot of work! I hope that you realise that I am still in the process of adding to/adjusting the trams...
Hey, thanks! Having a list like that is helpful, even if it's out of date.