Pixelmon Mod

Ok, I think that they should make a feature where you can type the pokemon name and and the game will track if one spawns near you, like the global message for legendaries.

There's already a side mod for this called Gameshark, but I do like the idea of chat messages being sent when a desired Pokémon spawns.

Chat messages being shown when a specific Pokémon spawns may already be possible through Pixelmon Broadcasts, provided the Pokémon is one of the types it supports. This is a server-only mod, though. Custom Pokémon tracking may be getting added eventually.