Hi, I'm FL, a few ones who managed to make a full game using Essentials (Pokémon Island). Several times I'm asked how to make a pokémon game, so I here to give tips and recommend guides/sites/resources about making a game. I focus on a game made using Essentials. And yes, I'm bad at writing.
Keep in mind that making a full game requires a iron will, a good portion of planning and lots of time, around 200 hours for the most sample ones but I estimate that I spend more than 1500 hours making my game until now. Knowing about pixel art or script isn't necessary (except the basics), but your game get very better if you know.
Keep in mind also that any help to your project is a bonus! Don't wait to get a scripter/pixel artists to make your game or is high probable that you don't find someone to help your game and you give up. Don't try to master all areas (script, pixel art, level desgin, story, audio). Ideally everyone needs specialize in the area that he is better. I concluded that the best is to make the game and putting placeholder graphics/system when you can, and when you find someone to help you, just change these things.
A very good guide is How to use Essentials. Attention for the first item! I suggest for only starting using Essentials after learning about 90% of event commands do. Make a test project and test these commands.
Remember: As more you train before, better your game will be. Experience is very important in several aspects, even in game design! The more games that you make, you will be better in making games.
Planning and taking decision
Planning is VITAL for big projects. It's VERY easier to correct problems or restruture things in this stage than later on. I suggest you to think about, at least, 90% of bosses (AKA GYM Leaders, Team Leaders and rivals) and they characteristics before start making the game, as well other impactful things like 90% of places/locations/main points to define the game main phases.
There some decisions that you need to take before making the game, otherwise you will have a big rework like using charsets/tilesets of generation 3 or generation 4/5. Avoid rework because the time that you take to do two times the same thing can be the time that you release you game earlier or that you can make extra features. This isn't a prohibition, so if you notice that some bad decision make a huge bad impact in the games, sometimes rework worth it. Analysis is fundamental.
Some people make the game only for himself, some make for making success with everyone plays and some make for a combination of these two. It's out of scope of this guide about which of these is the right/wrong, but I suggest you to make a game for yourself if you are other person. Think about a player that thinks in a similar way of you. Keep in mind that if you like to everyone enjoys your game remembers the general opinion, example: You love hard games, but the average players doens't like, so make the game (at least in the start) no so hard.
Remember that all players, even the non so smart ones, will play the beginning part, but not all will play to the final part, so don't make the firsts hours of gameplay too hard or too boring. If the first hours of gameplay aren't too interesting, the majority of players will give up of playing without reaching an ultra-super-cool climax, so make the beginning interesting too.
I suggest you to make the custom secondary things with no much impact in the gameplay (like extra Pokédex/Pokégear screens) and visual things (like redone the pictures) after the main game is practically done. So is easier to update the game for a newer Essentials version. Other advantage is that the beta testers can play the beta version and give the feedback while I make these things, and if I can't continue making the game there's a full game already done. If you know how to handle with it, the feedback is vital, pointing where you should improve.
First of all, I suggest you to use the latest version of Pokémon Essentials and updating the version before making the big script changes and/or a little before releasing a playable version. Every time that you change something in the scripts, remember to put some tag (like '#newscript') so you can easily find all changes with Ctrl+Shift+F. The new versions come with several bug fixes and new features, so the update time worth it except if you spend several hours to finish the update (to copy the script changes or other things). Sometimes the updates come with some bugs (like the trades stopped working), but generally is easy to find a fix in the Essentials forums, so don't be afraid of the updates because this.
The best graphic pack that I ever seen is the PHGC 7.0. I prefer to use the original outside tiles and extended inner and cavetiles rather than the new ones because that the old have even more tiles and is more easy to make different combinations with a bigger tileset, despite the lag.
DON'T REINVENT THE WHEEL! Before making resources, search if them already exist! Sometimes you find them better made that you can done! The reverse also apply, but, at least you have a base to do yours resources. If I take 1 hour to make a resource I prefer to, at least, search for 1 hour this resource.
I recommend you to search in the Essentials Wiki (about tutorials/scripts), in Pokécommunity and Deviantart, just search in the right section and use the right keywords in the search tools.
A very good way to learn how the things works is to look into the official games, SPECIALLY the graphics. But don't forget that the official games have several flaws, specially in the story. There severals gameplays at Youtube and several database in the internet (look specially at the wiki ones) if you need to check some part like the Pokémon Marts item lists, the trainers parties or a visual animation in that is better to watch in videos like the escalator and the doors opening.
Making the game
Eventually you find an obstacle to do something, but eventually manage to surpass these issues (except some custom things like DPP Pokédex, Triple Battles, among others). Anyway, SEARCH BEFORE ASKING A QUESTION. I strong suggest you to read the related pages at Essentials Wiki. If you wish a character that only appears at one day per week, look at wiki pages related to time. If you wish to make an island to appareas in the map after a certain event, look at the pages related with region map! Remember, knowledge is power! If even after you search and tried a good time you didn't found, so it's ok for ask.
With the Essentials kit you can do everything essentials for a pokémon game with pokémon systems, some non-essentials things like the Player Room or Secret Bases requires eventing/scripting. Keep in mind that is very hard to someone guides you how to make a complex feature, so enjoy the tutorials already released in the internet.
Keep track that you are doing! A certain level of organization is very important in any complex thing! A good example are the itens in the areas. If you keep a track of the items that you put in every area, is much easier to project a balance set of items for a new area, as well to correct mistakes and checks if you didn't forget to add an important item like a evolutionary one.
Frequently test the game or some changes may result in a great rework for you. Example: If you make the trainers for the entire game and, after this, you start testing. In the beginning you concludes that the game is too hard, so you need to rebalance all the trainers. Sometimes you only need to increase a few levels, sometimes you need to redo some teams. Fortunately the pokémon games have a relatively balanced system, including pokémon levels, exp gain, money and item cost, so this part is VERY easier than in a standard game. This apply to test not just trainers but also maps and theirs items, so avoid big/complex maps and strong items in the beginning. Pay attention in some details like the levels of your pokémon/latest boss when some items are avaliable in the marts at the official games.
When testing try to act like a not so good player, make the objectives and locations clear. I recommend focus in making the gameplay fun and challenging.
Backups are INDISPENSABLES. So do a backup schredule.
The time is a VERY important resource! Very, very, VERY few people can make the same game for more that five years without becaming tired of it, this without talking about raising a chance of someone of you team have a problem that may ruins the game/team. If you can do everything as twice as fast that other people, you can reduce a game that requires 8 years to 4, considerably raising the chance of finish a game! Beware of drop of quality! Some mistakes may backfire a bigger time lose with rework! Haste makes waste.
For my experience, I suggest you to spend some hours making your game every week. If you stop doing this, the chance of you give up of the project greatly increase. Keep the rhythm!
If you do a very simple game and keep around 10 hours per week making the game (without counting the time advertising it and things related), the game will be ready in a few months (around 4).
If you wish that everyone plays your game, remeber than advertising a game is even more important than making a good game.
Thanks for this helpful guide! Would it be possible for you to YouTube tutorials to show others the basics so they can improve?
This guide is strategy/tactical. there's no a easy way to do videos about these concepts. I may focus at some area (script, pixel art, level design, audio) to review good/bad examples or do operational tutorials (there some of these at web).
Anyway, I'm not good at making video tutorials, so I don't intend to do.