Pretty much what the guy above said. except for 2 and 4. 2) There might be tiles that aren't inveted to fit, or they couldn't find the right tile. 4) Unless it's part of the story like if you started in a region after the elite four or if your pokemon is reasonably leveled close to the wild pokemon, I won't reallly mind.ANYWAY Here's my major list
1) Pls edit the story line. IT SUCKS. I hate storylines that are filled with bull. like "Team Rocket killed all the pokemon now it's up to you to bring all of the pokemon back by defeating team rocket and collecting all the gym badges!" Like, what does the gym badges have to do with anything? honestly... and team rocket killing all the pokemon? That sounds rather improbable impossible
2) Grammatical Errors, hands (feet, head, nose, ears, everything) down. Disgusting. Just plain disgusting. "RYE VULL: PRUH FEZZ ER OKE SEZ U CAN OWN LEE TAYK WUN POKEMON!!1!" or for the champion "Haha your winung streeck endz heer!!!!1" Sort of ruins the whole "FINAL BATTLE EVERY THING HAS TO BE EPIC" Theme...
3) Unrealism. Your rival saying stuff like "HAHA U SUCK I WILL PWN J00 *SHOOT SHOOT* HE HEE U R DED" or beautifully designed city with no background. Like a gorged city with meteors bombarded around the field, or patches of oversized puddles or tonnes of rocks and ledges everywhere but it seems totally unreasonable, unless there's a story behind it and you expect to find out as you progress, but in the end, all it talks about is how the legendarys in the title screen came in. Hate that. You're wondering how this world became the way it is, and then nothing.
4) fakemon. I hate them. I just hate them. They can't replace pokemon. The creators give them such an absurd look, no matter how well shaded and detailed it is, and it doesn't look like a pokemon at all..Some I can stand, but when it comes to the legendaries, they're often way over detailed and they could easily be mistaken for a third evolution.
5) Completely random and useless. example: *guy walks up to you* "You look weak... We'll see who's the best trainer in the world! and then he walks away and you never see him in the story again. WTF?!?!!1!//
6) Stupid rivals. This includes what they say, why they battle you, and how strong they are. Examples: FIRST BATTLE: "Hey you stupid kid. I heard you gots a pokemon. Let's battle and see who's the top trainer!" k. So you talk about how I got my pokemon. and then all of a sudden you want to be the best trainer ever with your level 5 chikorita? mhm...*sends out Lv.42 mew" O_O "WTF!?" and finally
7) Wild Pokemon Problems? Self-explanatory. Hey look a sign! "Magma Mountain. Watch out for fiery pokemon!" Okay! Let's walk in the grass! *WILD FERALIGATR*-_-