RPG Maker isn't on its own. I've used it before, and it's awesome, but the biggest issue with Pokemon is not even the stats or the Pokemon list, but the database of EVERY UNIQUE INDIVIDUAL POKEMON YOU CATCH.
Every Pokemon in the Pokemon games was unique, even in the same species. This was decided based upon things called Individual Values and Effort Values. IVs were decided upon the moment the Pokemon was either caught or born, and each one was a random multiple of 2, between 0 and 32 I believe. Every EV was done through training, and you would gain certain EVs from battling certain Pokemon, up to a total of I think 255. They modified each individual stat. These are stats that were hidden in the game that players only ever got hints at.
You'll also need to keep track of each individual Pokemon's moveset. Plus, every Pokemon you catch has both a Trainer ID and a Secret ID.
You'll basically need to figure out a way to create a dynamic database for every Pokemon caught, and if you include multiplayer support, ways to represent that to each player. Arrays and JSON will likely be your best friends.
My suggestion: Get really really intimately familiar with the following features in Construct:
* Event Sheet Includes
RPGs are intense affairs. I'm working on a mere Action RPG and while it's coming along, it's a huuuuuuuuuge amount of work. There's a reason there aren't any complex RPGs out for Construct 2 yet. They're hard and they take a LOT of dedication.
That said, I wish you luck because it would be really cool to see someone do something like that with Construct. Because it certainly can!