[me I]

I am making a hack of Pokemon red, and I want to add a new Pokemon (with pokedex entry, cry,moves,etc.) I looked on the internet and can only find tutorials for adding Pokemon to the generation 3 games. Does anyone know what I can do?

[USC]

According to Bulbapedia, there's 190 indexes for Pokemon in the original series - in theory that gives you 39 creatures to add just using the existing structure.

That said, I don't know if there's enough free space in the ROM to actually store the new Pokemon's image, cry, and other data. You'll want to start mapping that out, as well as learning how the Pokedex data is structured. There are couple of guides here for you to start looking at:
http://www.romhacking.net/documents/522/
http://www.romhacking.net/documents/73/ (Placing Pokemon in the world map)

There's also some utilities that may help you make edits:
http://www.romhacking.net/?page=utilities&category=&platform=8&game=&author=&os=&level=&perpage=20&title=&desc=Pokemon&utilsearch=Go

[Chronosplit]

Most Gen 1-2 related things are over at Skeetendo, it's worth a look.

http://skeetendo.nfshost.com

[shadowmanwkp]

Most Gen 1-2 related things are over at Skeetendo, it's worth a look.

http://skeetendo.nfshost.com

Speaking of which, they have a topic on this exact subject: https://hax.iimarck.us/topic/6436/

[me I]

thanks guys. this has helped a lot.

[IIMarckus]

If you’re not already, you should be using the disassembly for your hack. The time to set it up is worth spending.

Here’s an example of how to add a new Pokémon to Pokémon Red with the disassembly.