Floor verb – To cause an unpleasant surprise for. Grass and floor are semantically related. In some cases you can use "Grass" instead a verb "Floor". Nearby Words: floored, flooring, floorboard
Grass verb – Cover with grass. Floor and grass are semantically related. Sometimes you can use "Floor" instead a verb "Grass". Nearby Words: grassland, grassy, grassed, grassing
In his interview with Spoony, Richard Garriott explains that this was because he had run out of space on the disk by this point, and realized that turning the floor and grass tiles into enemies actually made for a very difficult, strategically demanding battle worthy of the story's endgame.
Rank Inflation: The DexNav normally ranks you with Bronze, Silver or Gold Crown, based on if you have caught every Pokémon in a given area and by the encounter method (Grass/Floor, Surfing and Fishing).