EV training takes time and the ability to keep track of what EVs you have. It's also useless unless you start from a very low level (heck, level 5 is the best level to start). If you started EV training when it was level 50, it's already been loaded with EVs from other Pokemon its fought; EVs that it might not need. There's also a limit on how many EVs a Pokemon can have: a Pokemon can only have a maximum of 255 EVs to one stat, and it can only have a grand total of all EVs of 510. So if you've maxed out your EVs already, there's no point in EV training.
EVs are not the only thing that affect stats. A Pokemon's nature will raise one stat up by 10% and lower another stat by 10%. Check the RS FAQ for information on what nature affects what stat.
IVs also affect stats. IVs are determined the moment you receive/capture/hatch a Pokemon and CANNOT be changed. An IV value will range from 0-31 and there is a different value for six stats. Each point of IV adds one stat point to the stat it affects.
For example: Your Charizard's IV values are (Remember, just an example. I don't know your Charizard's IV actual IV value) 12 HP, 28 Attack, 5 Defense, 20 Sp. Attack, 18 Sp. Defense, and 30 Speed. That'll add 12 poins to your HP, 28 to attack, 5 to defense, 20 to Sp. Attack, 18 to Sp. Defense, and 30 to Speed.
There is not a set IV value for each species of Pokemon. It's randomly determind when you get it.
You can get a Macho Brace in the Viridian Gym. Check where Giovanni was standing after he leaves.
EDIT: You should ask this in the Pokemon GB Movesets and Strategies forum instead. They can explain EVs better and guide you through it better.
Until then, here's the best way to EV train a decent Pokemon.
Hatch the Pokemon you want at level 5 with a nature that you want (like I said, read the RS FAQ for information on natures). Grab a Zigzagoon or something with the Pickup ability. Battle wild Pokemon and gather up some Rare Candies. Use all of them on the Pokemon you just hatched.
Once you've reached a level capable of killing off most wild Pokemon, it'll be time to use it to fight and EV train. Fight ONLY the Pokemon I suggest to you in your other thread. Keep track of how many EVs you get on a piece of paper or something.