I never said anything about combining anime. What I meant was, Doraemon by itself has been running longer and has more episodes than Pokémon, Detective Conan, the Dragon Ball franchise, and Mobile Suit Gundam and its myriad spinoffs.
Pokémon: 276 (original series), 192 (Advanced Generation), 5 (banned)
Detective Conan: 451+
Dragon Ball: 153 (original series), 291 (Dragon Ball Z), 64 (Dragon Ball GT)
Gundam: 43 (Mobile Suit Gundam), 50 (Zeta Gundam), 47 (Gundam ZZ), 51 (Victory Gundam), 49 (Gundam Wing), 39 (After War Gundam X), 50 (Turn A Gundam), 52 (SD Gundam Force), 50 (Gundam SEED), 50 (Gundam SEED Destiny)
Doraemon: 2000+
That, and Doraemon has been airing nonstop since April 2, 1979.