the Tohoku Area and Hagano-Niigata Area passes are valid
So is the JR TOKYO Wide Pass, which is also issued by JR East.
These three passes have the same validity on the Tobu lines.
East Japan Railway [JR East]:
JR EAST PASS (Tohoku area) https://www.jreast.co.jp/e/eastpass_t/index.html
JR EAST PASS (Nagano, Niigata area) https://www.jreast.co.jp/e/eastpass_n/index.html
JR TOKYO Wide Pass https://www.jreast.co.jp/e/tokyowidepass/index.htmlthe pass is not valid on the regular Tobu trains to Nikko
Tobu-only trains are not completely excluded.
Tobu Railway operates two lines for Nikko City,
the Tobu Nikko Line for Tobu-nikko Station
and the Tobu Kinugawa Line for Kinugawa-onsen Station,
which lead in the different directions beyond Shimo-imaichi Station.
When you travel
between a JR station and a Tobu station in Nikko on the above line,
any of the above three passes lets you
take Tobu-only non-Limited-Express trains beyond Shimo-imaichi,
except for the section beyond Kinugawa-onsen Station.
(Kinugawa-onsen -- Kinugawa-koen -- Shin-fujiwawa is not covered.) the limited extress trains from Shinjuku to Nikko which are co-operated by JR and Tobu
In any of the JR-Tobu through Limited Express trains,
all the seats require reservation.
Your embarking or disembarking station
is not necessarily to be Shinjuku or Tobu-nikko.
You can choose a JR station from the following four stations:
Shinjuku Station in Tokyo,
Ikebukuro Station in Tokyo,
Urawa Station in Saitama Prefecture,
Omiya (with "O" pronounced long) Station in Saitama Prefecture.
Between Shinjuku and Tobu-nikko,
only one direct Limited Express train
is available for each way in a day,
the train going for Tobu-nikko in the morning
and the train going for Shinjuku in the evening.
The other three Limited Express trains
connect Shinjuku and Kinugawa-onsen for each way.
When you head to Tobu-nikko Station,
you can take
a JR-Tobu through Limited Express train bound for Kinugawa-onsen
then a Tobu-only Local train until Tobu-nikko.