Definitely. I'm blatantly stealing features, possible minigames, and dungeon/Gym puzzle concepts from other games all the time for my main project. Some of the games that I've lifted ideas from include Monster Rancher, Space Invaders, Star Fox 64, Animal Crossing, Harvest Moon, Pokemon Colosseum, Minish Cap, Ocarina of Time, Oracle of Seasons/Ages, Final Fantasy 9, and of course other Pokemon games (Pikachu's Beach!).
Even some ideas for how areas look are inspired by real-life places that I think would be interesting to explore in-game. Parts of NYC (Times Square, Lower Manhattan, Spanish Harlem, Central Park, the Highline, and Battery Park are a few), Barcelona, the Nile River Delta, Ibiza, and Mount St. Helens pre-eruption are some of the areas I've taken some cues from when designing areas and mapping them out. I have a horrible, noxious swamp that no one would possibly want to go to that is directly inspired by New Jersey and its people (zing!). Some area inspiration also comes from other games. My desert "route" takes cues from Uldum in World of Warcraft, with oases scattered around to break up the monotony as well as ancient, ruined aqueducts to prevent the player from just walking straight across and force exploration. I have a mountain that's partly inspired by Cleyra's Trunk in FF9. I have an optional, large ocean area that takes inspiration from Wind Waker's Great Sea. Other areas are just a given, you know, the ones that every Pokemon game ends up having; but I always try to give them a twist to keep the player interested.
There's a Performer Trainer class that parodies actual artists that the player can run into occasionally.
The commercials on TV are sometimes parodies of real ad campaigns. One is Corphish Crackers, "The snack that smiles back, Corphish!"
So yeah, I'm a thief. I have a ton of original ideas too, and putting the Pokemon spin on the concepts and ideas lifted from elsewhere does take some finagling, so I think my ratio of original stuff to stolen stuff is probably still good.
