Sauce

To do so, you’ll need to show a little restraint — as you start the game and see Bulbasaur, Charmander, and Squirtle surround you, ignore them. Walk away from the area and wait for them to relocate to your position.
After you complete this process four times, a Pikachu will appear with the three other starters, according to a report from Polygon. At that point, you can simply tap the Pokémon and capture it as usual, so long as the game’s embattled servers co-operate.
Many players will be looking to hunt down a Pikachu for its cuteness factor, but the monster offers a significant gameplay advantage, also. Electric-type Pokémon seem to be pretty rare in Go — at least for the time being — so the elemental advantage Pikachu possesses over water-type creatures presents a promising strategic opportunity.
The one downside to this trick is that it has to be pulled off at the very start of the game, so players will have to consider creating a new account if they’ve already started their Pokémon adventure. Pikachu can be caught during normal gameplay, but only this trick can ensure its appearance.

Sauce
First, here’s a couple of quick and generic tips, if you just want the secret method then skip to the next paragraph. So, in general, while playing Pokemon Go, you want to catch everything you can. It might seem dumb to catch your ten thousandth Pidgey, but the XP earned is decent, and it of course gives you candies that are important elsewhere. Also, make sure to tackle gyms often. Whether you’re trying to take them over, or just want to level it up, you’ll gain some valuable XP.

OK, now that you know the general ways, here’s the specific one for how to level up fast in Pokemon Go. First off, you’ll need a lot of Pidgeys (Weedles and Rattatas are OK, but Pidgey is best). You’ll also need a lucky egg, this is the valuable item that doubles your XP. Now, once you have these two things you should be good to go, but I’m serious, you need a ton of Pidgeys.

Once you have them, make sure you’ve got a lot of Pidgey candy. Transfer your Pokemon if you need more. The key is that evolving a Pidgey only costs 12 Pidgey candy, and each evolution gives you a whopping 1000 XP. You should be seeing the big picture now.

When you’re ready, pop your lucky egg, doubling the XP earned. Now go in and evolve everything you can, which should include like a dozen Pidgeys. This will give you a ton of XP and should jump you by a level or two depending on your current status. Once you’ve evolved everything you’ll probably have some time left on your lucky egg, so just go around and try to catch some more (use a lure if you feel like it). Evolve more if you can, it’s really the best and easiest way to gain XP. And that’s pretty much how you level up fast in Pokemon Go.

Credit to pcboss00
UPDATES
Update: seems we need to wait when it will release to Malaysia ler.....
Update 11 July 2016
Some rumors mentioned that pokemon go will launch on 27 july 2016. Be prepare guys!

Update 12 July 2016
Is this a good sign？

Update 13 July 2016
Heard about Europe and asia will be available in this week!

16 July 2016