Here are the models I can think of, off the top of my head. I may have missed one or two.
Models sold outside of Japan
Tamagotchi Angel
Tamagotchi Connection (V1)
Tamagotchi Connection V2
Tamagotchi Connection V3
Tamagotchi Connection V4
Tamagotchi Connection V4.5 (sold as "V4 plus" in some parts of the world)
Tamagotchi Mini
Tamagotchi Ocean
Tamagotchi P1 (1996/1997 model first generation)
Tamagotchi P2 (1996/1997 model second generation)
Models sold in Japan
Angel Gotchi
Arukotchi
Chibi Tamagotchi (Mini Tamagotchi)
Devil Gotchi
Doraemontchi
Doramitchi
EnTama
EnTama CYOI
Genjintchi (Caveman Tamagotchi)
Hanerutchi
Hanerutchi 2
Home Deka Tama
Home Deka Tama "Game King"
Kakeibo
KeiTama
KeiTama Akai Series
Mezamatchi
Mori No Tamagotchi (Morino / Forest / Garden)
Mothra Tamagotchi
Oden-kun Tamagotchi
Osutchi and Mesutchi (Osu-Mesu)
Santa Clautch
Tama Fure
Tama School (TamaSuku)
Tama School 2 (TamaSuku 2)
Tamago-chu
Tamagotchi P1 (1996/1997 model first generation)
Tamagotchi P2 (1996/1997 model second generation)
Tamagotchi Plus
Tamaotchi
Umi No Tamagotchi (Ocean Tamagotchi)
UraTama
Yasashii
Pictures and information about many of these models can be found on
https://www.Tamenagerie.com