94 is a glitch Pokémon found only by using gameshark codes to encounter a "gentleman" Pokémon trainer in the wild and using the steal trainer Pokémon cheat before the battle shows the gentleman coming into view. It converts to Rhydon for the first time after catching it.

Pokédex screen

94's Pokédex screen has no information except weight and height (23' 0' HT and 880.6 LB)

Possible reason

It may be caused by the game trying to access the wild Pokémon data of the same hex as the gentleman trainer but since there is only trainer data the game loads some trainer data chunks which glitches when used as Pokémon data. The game sometimes succeeds in loading some Pokémon data as many times 94's name appears as the name of one of the Pokémon in that area (like Rattata in Route 1) yet it is still the same glitch.