I will give three big notices.
1: In the beginning of almost any Pokemon movie, you will see a similar planet to ours.
The Pokémon world looks and acts like the real world in terms of
geography. Each have landforms, oceans of water (the Oceanic Museum
has an exhibit claiming over two-thirds of the world is covered by
water, the same as Earth), and temperatures to support life - meaning
that the Pokémon world is about the same size and same distances from
its sun as the real world. Misty even directly refers to the Pokémon
world as Earth in Pokémon Heroes. However, if the Pokémon world is not
Earth, it must be similar, having a similar moon, similar climates,
and so on, which explains the similar tides. Many different theories
exist as to exactly how the Pokémon world relates to our own.
2: In the Anime, they have a few episodes where fish is eaten.
Animals have been seen in the anime. They were more common in the
original series as there weren't as many Pokémon species introduced at
the time. A picture book based on the Pokémon anime once featured a
dog walking past Ash and his friends, and a piece of concept art of
the residents of Pallet Town featured a cat. Birds can also
occasionally be heard in the background. Foods that contain meat
products, such as hamburgers and chicken are often seen.
3: The regions are based off of places on Earth.
Regardless of their proximity, the people of Johto and those of Kanto
are set apart by many cultural differences. Kanto is based on the real
Kantō region in Japan. Compared to the traditional Kansai region
(where Johto is based), Kanto is modern and technological, which is
reflected in the look of the cities and the buildings like the Pokémon
Lab of Cinnabar Island and the Power Plant. This fact is also
reflected in Kanto being the only Pokémon region without any legends,
myths, or traditions related to Pokémon, and being the centerpoint for
innovation, with the Poké Ball's ultimate upgrade, the Master Ball,
being recently invented by Silph Co. The soil of the Kantō region is
volcanic, referencing the in-game Kanto region's inability to maintain
a Berry crop in Generation II, Generation III and Generation IV.
People from Kanto are considered to be sophisticated, reserved and
formal. Kansai and Kantō, however different, are the two most
important areas of Honshū, the largest island in Japan, and, much like
Johto and Kanto, represent a harmony of contrasting cultures living
together. The cultural divide is most noticeable in the games, as the
player talks to and learns about the denizens of both regions. Tokyo,
which the commercial Celadon City and the financial Saffron City are
based on, is the most important commercial and economic center of
Japan. Yokohama, which Vermilion City is based on, is the main and
largest seaport of Japan. Although some of Unova is geographically based on New York, the creators of the region took some liberties in regards to the surrounding areas. Clearly, the largest city in Unova, Castelia City, is based on Lower Manhattan, but to the immediate north of Castelia is (as opposed to a continuing metropolis as in real life) a vast desert. Nimbasa City, which is to the north of Castelia City, could be a reference to Broadway, which is located in Manhattan. The division of Unova may also be a reference to the Boroughs of New York City. The Skyarrow Bridge is a reference to the Brooklyn Bridge, which connects Brooklyn and Manhattan.
All my sources come from Bulbapedia.