Some Pokémon with backwards names are Ekans, Arbok, Rotom, Girafarig, Ho-oh, Eevee, and Alomomola. These are among many Pokémon with some sort of pun or reference in their names.
As of the sixth generation of Pokémon, there are four Pokémon with palindromes as names. This means that their names are spelled the same forwards and backwards. The first Pokémon to use this pattern of naming was Eevee from the first generation. Ho-oh and Girafarig were introduced in the second generation. Finally, Alomomola was added in the fifth generation.
Aside from Pokémon with palindrome names, there are also several Pokémon whose names are a word written backwards. The most popular and widely known of this type are Ekans and Arbok from the first generation. Ekans and Arbok are both designed to look like snakes. Therefore, Ekans is simply "snake" backwards. While Arbok's name backwards, "kobra," is not a word, but it is phonetically the same as "cobra," a type of snake. Finally, the fourth generation Pokémon Rotom's name is the word "motor" backwards. This is a reference to the ability of Rotom to assume the shape of certain motor-based appliances, namely a washing machine, refrigerator, lawn mower and microwave.
While these are the only currently known Pokémon with backwards names, there are many other Pokémon with special names.