I understand that this hack can be difficult at times. However, if you plan ahead like what I did, this hack shouldn't be so hard. It mainly depends on where you start and especially what Pokemon you are using.
As for you're team, I'll give you the methods of evolution for those you have right now (Even if you already have the idea).
Saragotchi: Evolves at level 50.
Charbulble: Evolves at level 30.
Audior: Evolves at level 35.
Gastly: this has two evolutions
* Evolves into a Frozone with an Ice Stone (Available at the Celadon Department Store; you can go south of Cerulean without meeting Bill)
* Evolves into a Hellraiser with a Fire Stone (Also Available at the Celadon Department Store)
Batrachian: It's fully evolved
* Saragotchi is going to take a long time to level up and evolve, so it might be wise to replace it.
* Audior's evolution and Batrachian have rather low base stats, so replacing them later might be a good idea. It's you're choice if you want to keep using them however.
* Either of Gastly's evolutions work well, but I personally would prefer Frozone due to the potent bolt beam (Thunderbolt via TM and Ice Beam at Level 51) combination. Furthermore, You can use the TM 13 from the Celadon Department store rooftop to teach it a good STAB move early on.
There is a link to the Github on the top of the first post (And right here:
https://github.com/CameruptQDX/PF-Roaming-Red.) You can search for Pokemon learnsets and evolution methods by doing the following:
Data --> evos_moves.asm --> search the Pokemon you want to know about
Also, you can find out about base stats and TMs each Pokemon learn from doing this:
Data --> baseStats --> select the Pokemon you want to know about
There are also some other things that the Github can inform you on, but I think I gave the general idea as it is.