I'm going to use the equations on the page about Tall GrassThe percentages indicate how much of a chance you have into running into a given Pokémon when you go into the grass. For example, if in HeartGold you go into the Violet City side of Dark Cave and run into a wild Pokémon, there's a 60% chance of it being a Geodude, a 39% chance of it being a Zubat, and a 1% chance of being a Dunsparce. The higher the percentage, the more likely you are to find the corresponding Pokémon, so you can expect to see mainly Geodude and Zubat in Dark Cave, more Geodude than Zubat, and you'd have to be pretty lucky to find a Dunsparce.I'm reading about pokemon that you can catch on each route on bulbapedia but I am confused about the percentages under rate. What do these mean?
Also why is it different on some other pages where it just says rare, common or average?
As for rare/common/average, they're just placeholders until someone can get ahold of the actual numbers and add them instead.
Tall grass - Bulbapedia, the community-driven PokÃ©mon encyclopedia
It still has descriptions such as Very Common, Common, Semi-rare, Rare and Very Rare. Are there percentages that let me know which one would be which?
Using your example, 60% chance of running into Geodude then would that be Very Common or Common? Is there a way I can find out?