Just some clarification before I begin because I know some of you say "Game Freak" or "Nintendo" on these matters. Neither of them help in the creation of Pokemon. None. They only help in making the games, which means the closet they come to creating Pokemon is creating their sprites. So I will probably never mention Gamefreak of Nintendo in this thread after this paragraph.
So every once in a while someone says "Wow, the Pokemon company must really be running out of ideas." Don't deny it, you've said it at least once after seeing some of those Pokemon that look like the Pokemon company grabbed it right out of their ass, or from the ice cream man on the corner. But are they really running out of ideas? Or are they just throwing in some of those lamer ideas in with the cool ones to do what the Pokemon Company loves doing: Creating balance. Every generation of Pokemon needs a Grimer, Dunsparce, Gulpin, Vanillite, or some other Pokemon that just makes you sigh in disappointment. Those same generations also have their fair share of epic Pokemon. Charizard, Steelix, Blaziken, Snivy, or other Pokemon that make you have a fangasm. If the company were truly running out of ideas, we'd see a growing trend in lame Pokemon paired with a shrinking trend in awesome Pokemon.
However, the trend tends to keep the same: Several awesome Pokemon, many neutral Pokemon, and a few lame Pokemon. What does that mean? The Pokemon Company hasn't run out of ideas, far from it, they're just practicing something they love about Pokemon: Balance. It's the same reason Charizard wasn't Fire/Dragon from the beginning, every type has a weakness, and several other occurrences that we may have not agreed with because our previously badass Pokemon isn't so badass anymore.
So, as proof that the Pokemon Company has plenty of ideas remaining, here's a list of several ideas that the Pokemon Company can, and probably will, use to create Pokemon.
Inanimate Objects:
Sludge, Gears, Magnets, the Pokemon company has it's fair share of inanimate objects that become Pokemon. Normally these are the ones we "boo" at because it appears boring. I mean, a fire breathing chicken is more fun than cold floating ice cream...still delicious, though. Here's a list of all inanimate objects that can become Pokemon. Oh and because of the large variety of them, I'll put them into categories.
All kinds of Furniture: Who doesn't want a Pokemon you can relax in while it beats the crap out of your enemies? Well...a lot of people. In fact furniture is the most joked about objects to become Pokemon. Even more so than food.
Most kinds of Food: Other than seeds, ice cream, and Pokemon that appear as animals that become food, food normally doesn't end up becoming Pokemon. There are probably as many dishes as their are humans, which means if the Pokemon Company doesn't make each one into a Pokemon, that means one Pokemon with around 7 billion different forms. That's taking "Catch 'em all" to a whole new level of crazy.
Most appliances: Ever want your Nintendo 3DS to suddenly become a Pokemon? No? Oh you just wanted it to be a portal to the Pokemon world. Well one day you might get the former. Appliance Pokemon are truly rare. the Magnemite line, Klink line, and Litwick line are literally the only ones.
All tools: Wrenches, kitchen knives, unless you count Kadabra and Alakazam's spoons, no tool has become a Pokemon, not even medicinal tools such as pills and syringes. Now Honedge's line are weapons, not tools. Technically Voltorb and Electrode are tools, being literally living Pokeballs, but since Pokeballs aren't actual tools in the real world that can capture creatures, they don't count.
Most Weapons: Other than Honedge's line, weapons have not made it into the over 700 Pokemon we have nowadays. Why? Well how would you feel if a game had a living gun that your son/daughter befriended and would fight other people using said living gun? Not too good. It's quite possible things like a Bow 'n Arrows, bombs, and similar pre-gun era weapons may become Pokemon, but it's a careful line the Pokemon Company has to tread or they'll end up getting sued by parents.
All Modes of Transportation: Ok, honestly I want these. I played Bravely Default, and in the game there are two summons, Promethean Fire and Hresvelgr, who appear as a fire breathing dragon train and a tornado laser shooting airplane falcon. They're epic. I would love if the Pokemon Company could make epic Vehicle Pokemon like those two summons.
Natural Inanimate Objects: Planets, Comets/Meteors, Galaxies, and pretty much the truly massive objects in our universe have yet to be made into Pokemon. Yes Solrock and Lunatone are Pokemon, but come on, they're rocks in the shape of the sun and moon called the Meteorite Pokemon. The Pokemon Company needs to make something better, and I'm sure they will.
Animate Things:
Plants, Animals, Bacterium, Viruses. There's a lot of stuff that can be made into Pokemon in the living world. Most Pokemon represent some animal paired with some element or force of nature. How many species have we discovered so far? 8.6 million, that's 11961.057 times the amount of Pokemon we have, and remember that several lines are based on similar species (Shinx and Litleo both represent lions, for example). And that's just those we know about. Scientists estimate that over 86% of all species living on the Earth today have yet to be discovered. That's millions of species we've yet to discover. Not to mention it's believed that 99.99% of all species on Earth have gone extinct, and only 00.001% of that percentage have been fossilized. That obviously mean the Pokemon Company can make at least 66 thousand generations not counting the living and extinct species of plants and animals being discovered. Of course I don't have the time and patience to list the over 8 million pokemon they can make, so I'll just list the ones off the top of my head. Note that most of these aren't specific species, but just the family of animals that share similar names.
Flamingo
Stegosaurus
Velociraptor (no, Archeops is not one, it's supposed to be a Microraptor/Archaeopteryx mix)
Komodo Dragon
Toucan
Vultures
Turkey
Iguana
Tiger
Lemur
Roadrunner
Terror Bird
And these are those that I can think of. I'd carry onto the mythical creatures, but my brain is already spinning from all these ideas. Anyways, if you want a list of some animals here ya go:
http://lib.colostate.edu/wildlife/atoz.php?sortby=Genus_Species&letter=ALL