Easiest way to earn EXP in Pokémon?

The VS Seeker was the absolute best thing in the franchise. I spent countless hours just re-battling trainers and getting my Pokémon to super-high levels! Was especially awesome since you got that item right in Vermillion City so you could use it early into the game. Yay FR/LG. 8D

 

Gotta agree with Sheep here, the VS. Seeker is amazing. Rebattling trainers is awesome, since you get experience as well as money. Not only that, but those trainers would gradually increase in level and some of their Pokémon would evolve as well. It was really fun and useful to train up!

 

Besides the vs Seeker, in X and Y the battle chateau was the best place to be. The Audinos greatly increased my levels, and that place didn't want me to leave. In OR/AS however, you could just check your map and rebate trainers. I did that a lot. And it helped a lot.

 

Vs. Seeker and Elite Four at certain levels.

 

Elite Four in D/P and original R/S. Good times. Used Exp. Share and Amulet Coin so much.

 

In gen V, Audino grinding is the way to go in my opinion!

 

In X/Y, reach the highest rank possible in the Battle Chateau and issue a Black Writ Challenge. This challenge lasts 24 hours and you get all brand new trainers every hour. Equip a Lucky Egg to the Mon you want to train, and use your Exp. O Power (preferably Lv. 3). This helped me tremendously when I was in the midst of completing the National Pokédex.

 

In Generation 5, as most of us probably know, grinding against an Audino while holding a Lucky Egg will yield a ton of awesome experience. It is personally my favorite kind of grinding because it doesn't take long at all (if you can find an Audino)

 

murdering audinos and such

 

I typically just grind on the Elite Four, since I'm not too worried about EXP and whatnot. Before that I just grind in the wild, but I've never had to grind more than a couple levels at once.

To level up my party very fast in XY, I used the restaurants in Lumiose. Restaurant Le Wow was my go-to spot, and it gave very good results, plus a lot of money! Blissey Bases in ORAS also give insane amounts of EXP when coupled with an EXP power and Lucky Eggs.

 

Audino is probably really the place to be from Gen V on. In Gen VI, you can fight those Audino girls in the Battle Chateau, easy EXP right there Before that, you're probably the best off just running through the Elite Four a few times.

 

With games on the DS, VS. Seeker. That was the stuff, man. If you found a trainer that was really easy to combat with one Pokémon, you could basically just spam that one trainer. Other than that, I'd suggest the Pokémon League. They had good grinding capabilities for higher leveled Pokémon, but it couldn't be easily done with lower leveled Pokémon.

If we were talking about ORAS, then... Blissey bases. Blissey bases without a single doubt. If you snag a lucky egg from a Pelliper, Blissey bases can boost you up to over 75,000EXP at a time. Seriously, that stuff is insane. If you need a Blissey base, the QR codes can easily be found in Google Images. c:

 

As others have mentioned, utilising the VS Seeker and going on Audino massacres while holding a Lucky Egg are the best ways to go. (Sorry Audinos but it has to be done for the glory of Pokémon training!)