Could you tell me where I can get a Growlith in Pokemon Blue?

I don't think you can get Growlithe in Pokemon Blue.

It is possible to get him in Pokemon Blue!
Remember that Level 7 Pokemon cheat I put in a few weeks ago? Well do the whole pause before you see the JR. TRAINER thing, then either FLY or TELEPORT then head to Vermilion CITY, go to the grassy area where lots of trainers are (after DIGLETTS CAVE), and head down until you see a GAMBLER who has a POLIWAG and a HORSEA, after you beat him FLY or TELEPORT back to Cerulean City, go up NUGGET BRIDGE, when the menu pops up, press B, you'll now be in battle with a level 7 GROWLITHE.

HINT- To stop the GROWLITHE from using ROAR on you, take a Pokemon who knows either SING or SLEEP POWDER to make it easier!!

I don't know where to get it but an easy way is trading.

Trade it from Red is your best bet.

You have some choices...

...You can either import it from Pokemon Red Version...

...Or you can exploit the Mew Glitch to obtain it if you have, by any means, no second GameBoy or Link Cable, or anyone who is willing enough to do it with you.

If you ever wanted to do the Mew Glitch to get Growlithe, by the way, since it doesn't exist in this version, I have it here for you...

The six ways to get Mew...

1. First, find a Trainer, any Trainer at all, and battle him/her.

After defeating that Trainer, find a Pokemon of yours that has a Special stat of 21 or 277. Now, put it first in your party.

Go where ever you can find a Ditto and battle it. Let it transform into your Pokemon with the 21 Special stat. After it transforms, defeat it. It is safe to switch out to a different Pokemon now to beat it, if desired.

Fly to Lavender Town and walk off the west end of town. Mew should appear...

2. Walk past Nugget Bridge and left at the end of it. See that grassy bridge right there? Well, go in there, but DO NOT VERSUS THE TRAINER. Now, walk around in the grass until you find an Abra. Catch it when you see it, a simple PokeBall without dealing damage should do the trick. SAVE THE GAME. Now, if the Abra was sent to the PC, store 2 of your Pokemon and withdraw Abra. Why deposite 2 Pokemon? Because you need an extra space in your party to staore Mew. With Abra and 4 other Pokemon in your party, Save the game again, if you want. Head up Nugget Bridge, then swing to the right. You will see a Trainer facing the right, he's one of the first Trainers that will enter your screen. Well, you're going to have to battle him. After doing so, walk into Cerulean City again, then walk back out onto Nugget bridge and head a left where the Trainer in the grass is (I'll explain later why you need to do this). What you'll want to do now is position yourself to be directly above the Trainer, but have him still be one step-square below the screen's view. To give you a feeling of what I mean, position yourself on the left side on the grassy bridge, just down far enough so that you can see 4 grass squares in a square formation below you. Got that? Now SAVE. When you're ready, step down one square and press Start really fast. If done correctly, your manu should pop up, and the Trainer should be to the left of the menu. Now go to your Abra and tell it to Teleport to the Cerulean Pokemon Center. Once you arrive, your A, B, and Start button will not function.


Now, you can battle one of two Trainers now.


You can either battle the first Trainer in Misty's Gym (This way is easier) or you can battle the Trainer on the Route to the right of Nugget Bridge with the Slowpoke. Let's go with the Gym Trainer now, though.

When you walk into the Gym, walk in front of the swimming Trainer and defeat him. Now walk out side of the Gym. Save the game, buy PokeBalls, heal your Pokemon, whatever you need. When you're ready, walk up Nugget Bridge. While walking, your menu should suddenly pop up. Simply press B, and... MEW!

3. You can do the above obtainable, but instead of using Teleport, you can use Fly, if you have it.

4. Find a Trainer, any Trainer, and battle him/her. After the battle, fight a wild Pokemon that might have a spacial stat of 21 or 277. If that Pokemon does have a special stat of 21 or 277, then you should be able to find Mew by either going into the route where the Trainer was that you battled before the Pokemon battle or be able to walk off the west end of Lavender and be able to encounter Mew.

5. Through a GameShark.

6. Through encountering Error Pokemon on the east shore of Cinnabar Island or Seafoam Islands. To encounter Mew as an Error Pokemon, try starting the game with your name as "Xavier" (without the quotes), you may be able to find high level Mews, but I cannot promise this.