#If we disqualify the Tommy Westphall Universe…

An issue with the Tommy Westphall universe is that many shows are only linked by Easter eggs (e.g. the TARDIS is in the background of a single shot, things like Morley cigarettes or the Yoyodyne company exist), which isn't really in the spirit of the question.

Also, plenty of shows in that universe are not at all intended to be in continuity with each other. For instance, CSI: Miami as it's own show is not intended to be in continuity with either The Adventures of Superman or The Addams Family. So if we only count shows that have explicit, intentional links to all the other shows in the shared universe, the biggest is:

##The Super Sentai franchise (41 Shows and Growing)

English speakers may be more familiar with Power Rangers, which takes fighting footage from this Japanese series and dubs it in English while splicing in original English footage. It began in 1975 with Himitsu Sentai Gorenger and now produces a new show every year, with the 2017-2018 show being Uchu Sentai Kyuranger.

The 35th show (Kaizoku Sentai Gokaiger) was an anniversary show that made it abundantly clear that it was in continuity with all the previous shows. The first episode had all the protagonists appear together (played by suit actors, which also happened in the original shows) and some of the non-suit actor original cast members reprised their roles over the course of the series.

Each subsequent show is also in continuity with the show before it, with the final shot of each show showing a hand-off between the Red Ranger of the current show and the Red Ranger of the next show. There is often a team-up episode between the current show and previous show as well, although nowadays, those are usually done in theatrical films. Speaking of which…

##If we count movies, then the Super Sentai, Karen Rider, and Metal Heroes shared universe (84 Shows and Growing)

You said that movies don't count for this purpose, but if it did, there is the Japan-only theatrical movie Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z, which is a crossover between the Super Sentai franchise, the Kamen Rider franchise (26 shows), and the Metal Heroes franchise (17 shows). Note that Super Sentai is represented by Kaizoku Sentai Gokaiger, the anniversary show listed above. So if movies were allowed, this would be a crossover universe with 84 shows at the time of this writing.

If we disqualify the Tommy Westphall Universe…

An issue with the Tommy Westphall universe is that many shows are only linked by Easter eggs (e.g. the TARDIS is in the background of a single shot, things like Morley cigarettes or the Yoyodyne company exist), which isn't really in the spirit of the question.

Also, plenty of shows in that universe are not at all intended to be in continuity with each other. For instance, CSI: Miami as it's own show is not intended to be in continuity with either The Adventures of Superman or The Addams Family. So if we only count shows that have explicit, intentional links to all the other shows in the shared universe, the biggest is:

The Super Sentai franchise (41 Shows and Growing)

English speakers may be more familiar with Power Rangers, which takes fighting footage from this Japanese series and dubs it in English while splicing in original English footage. It began in 1975 with Himitsu Sentai Gorenger and now produces a new show every year, with the 2017-2018 show being Uchu Sentai Kyuranger.

The 35th show (Kaizoku Sentai Gokaiger) was an anniversary show that made it abundantly clear that it was in continuity with all the previous shows. The first episode had all the protagonists appear together (played by suit actors, which also happened in the original shows) and some of the non-suit actor original cast members reprised their roles over the course of the series.

Each subsequent show is also in continuity with the show before it, with the final shot of each show showing a hand-off between the Red Ranger of the current show and the Red Ranger of the next show. There is often a team-up episode between the current show and previous show as well, although nowadays, those are usually done in theatrical films. Speaking of which…

If we count movies, then the Super Sentai, Karen Rider, and Metal Heroes shared universe (84 Shows and Growing)

You said that movies don't count for this purpose, but if it did, there is the Japan-only theatrical movie Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z, which is a crossover between the Super Sentai franchise, the Kamen Rider franchise (26 shows), and the Metal Heroes franchise (17 shows). Note that Super Sentai is represented by Kaizoku Sentai Gokaiger, the anniversary show listed above. So if movies were allowed, this would be a crossover universe with 84 shows at the time of this writing.

#If we disqualify the Tommy Westphall Universe…

An issue with the Tommy Westphall universe is that many shows are only linked by Easter eggs (e.g. the TARDIS is in the background of a single shot, things like Morley cigarettes or the Yoyodyne company exist), which isn't really in the spirit of the question.

Also, plenty of shows are not intended at all to be in continuity with each other. For instance, CSI: Miami as it's own show is not intended to be in continuity with either The Adventures of Superman or The Addams Family. So if we only count shows that have explicit, intentional links to all the other shows in the shared universe, the biggest is:

##The Super Sentai franchise (41 Shows and Growing)

English speakers may be more familiar with Power Rangers, which takes fighting footage from this Japanese series and dubs it in English while splicing in original English footage. It began in 1975 with Himitsu Sentai Gorenger and now produces a new show every year, with the 2017-2018 show being Uchu Sentai Kyuranger.

The 35th show (Kaizoku Sentai Gokaiger) was an anniversary show that made it abundantly clear that it was in continuity with all the previous shows. The first episode had all the protagonists appear together (played by suit actors, which also happened in the original shows) and some of the non-suit actor original cast members reprised their roles over the course of the series.

Each subsequent show is also in continuity with the show before it, with the final shot of each show showing a hand-off between the Red Ranger of the current show and the Red Ranger of the next show. There is often a team-up episode between the current show and previous show as well, although nowadays, those are usually done in theatrical films. Speaking of which…

##If we count movies, then the Super Sentai, Karen Rider, and Metal Heroes shared universe (84 Shows and Growing)

You said that movies don't count for this purpose, but if it did, there is the Japan-only theatrical movie Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z, which is a crossover between the Super Sentai franchise, the Kamen Rider franchise (26 shows), and the Metal Heroes franchise (17 shows). Note that Super Sentai is represented by Kaizoku Sentai Gokaiger, the anniversary show listed above. So if movies were allowed, this would be a crossover universe with 84 shows at the time of this writing.

#If we disqualify the Tommy Westphall Universe…

An issue with the Tommy Westphall universe is that many shows are only linked by Easter eggs (e.g. the TARDIS is in the background of a single shot, things like Morley cigarettes or the Yoyodyne company exist), which isn't really in the spirit of the question.

Also, plenty of shows in that universe are not at all intended to be in continuity with each other. For instance, CSI: Miami as it's own show is not intended to be in continuity with either The Adventures of Superman or The Addams Family. So if we only count shows that have explicit, intentional links to all the other shows in the shared universe, the biggest is:

##The Super Sentai franchise (41 Shows and Growing)

English speakers may be more familiar with Power Rangers, which takes fighting footage from this Japanese series and dubs it in English while splicing in original English footage. It began in 1975 with Himitsu Sentai Gorenger and now produces a new show every year, with the 2017-2018 show being Uchu Sentai Kyuranger.

The 35th show (Kaizoku Sentai Gokaiger) was an anniversary show that made it abundantly clear that it was in continuity with all the previous shows. The first episode had all the protagonists appear together (played by suit actors, which also happened in the original shows) and some of the non-suit actor original cast members reprised their roles over the course of the series.

Each subsequent show is also in continuity with the show before it, with the final shot of each show showing a hand-off between the Red Ranger of the current show and the Red Ranger of the next show. There is often a team-up episode between the current show and previous show as well, although nowadays, those are usually done in theatrical films. Speaking of which…

##If we count movies, then the Super Sentai, Karen Rider, and Metal Heroes shared universe (84 Shows and Growing)

You said that movies don't count for this purpose, but if it did, there is the Japan-only theatrical movie Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z, which is a crossover between the Super Sentai franchise, the Kamen Rider franchise (26 shows), and the Metal Heroes franchise (17 shows). Note that Super Sentai is represented by Kaizoku Sentai Gokaiger, the anniversary show listed above. So if movies were allowed, this would be a crossover universe with 84 shows at the time of this writing.

#If we disqualify the Tommy Westphall Universe…

An issue with the Tommy Westphall universe is that many shows are only linked by Easter eggs (e.g. the TARDIS is in the background of a single shot, or things like Morley cigarettes or the Yoyodyne company exist). Also, plenty of shows are not intended at all to be in continuity with each other (for instance, CSI: Miami as it's own show is not intended to be in continuity with either The Adventures of Superman or The Addams Family). So if we only count shows that have explicit, intentional links to all the other shows in the shared universe, the biggest is:

##The Super Sentai franchise (41 Shows and Growing)

English speakers may be more familiar with Power Rangers, which takes fighting footage from this Japanese series and dubs it in English while splicing in original English footage. It began in 1975 with Himitsu Sentai Gorenger and now produces a new show every year, with the 2017-2018 show being Uchu Sentai Kyuranger.

The 35th show (Kaizoku Sentai Gokaiger) was an anniversary show that explicitly showed that it was in continuity with all the previous shows. The first episode had all the protagonists appear together (played by suit actors, which also happened in the original shows) and some of the non-suit actor original cast members reprised their roles over the course of the series.

Each subsequent show is also in continuity with the show before it, with the final shot of each show showing a hand-off between the Red Ranger of the current show and the Red Ranger of the next show. There is often a team-up episode between the current show and previous show as well, although nowadays, those are usually done in theatrical films. Speaking of which…

##If we count movies, then the Super Sentai, Karen Rider, and Metal Heroes shared universe (84 Shows and Growing)

You said that movies don't count for this purpose, but if it did, there is the Japan-only theatrical movie Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z, which is a crossover between the Super Sentai franchise, the Kamen Rider franchise (26 shows), and the Metal Heroes franchise (17 shows). Note that Super Sentai is represented by Kaizoku Sentai Gokaiger, the anniversary show listed above. So if movies were allowed, this would be a crossover universe with 84 shows at the time of this writing.

#If we disqualify the Tommy Westphall Universe…

An issue with the Tommy Westphall universe is that many shows are only linked by Easter eggs (e.g. the TARDIS is in the background of a single shot, things like Morley cigarettes or the Yoyodyne company exist), which isn't really in the spirit of the question. 

Also, plenty of shows are not intended at all to be in continuity with each other. For instance, CSI: Miami as it's own show is not intended to be in continuity with either The Adventures of Superman or The Addams Family. So if we only count shows that have explicit, intentional links to all the other shows in the shared universe, the biggest is:

##The Super Sentai franchise (41 Shows and Growing)

English speakers may be more familiar with Power Rangers, which takes fighting footage from this Japanese series and dubs it in English while splicing in original English footage. It began in 1975 with Himitsu Sentai Gorenger and now produces a new show every year, with the 2017-2018 show being Uchu Sentai Kyuranger.

The 35th show (Kaizoku Sentai Gokaiger) was an anniversary show that made it abundantly clear that it was in continuity with all the previous shows. The first episode had all the protagonists appear together (played by suit actors, which also happened in the original shows) and some of the non-suit actor original cast members reprised their roles over the course of the series.

Each subsequent show is also in continuity with the show before it, with the final shot of each show showing a hand-off between the Red Ranger of the current show and the Red Ranger of the next show. There is often a team-up episode between the current show and previous show as well, although nowadays, those are usually done in theatrical films. Speaking of which…

##If we count movies, then the Super Sentai, Karen Rider, and Metal Heroes shared universe (84 Shows and Growing)

You said that movies don't count for this purpose, but if it did, there is the Japan-only theatrical movie Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z, which is a crossover between the Super Sentai franchise, the Kamen Rider franchise (26 shows), and the Metal Heroes franchise (17 shows). Note that Super Sentai is represented by Kaizoku Sentai Gokaiger, the anniversary show listed above. So if movies were allowed, this would be a crossover universe with 84 shows at the time of this writing.