What Goes in a Team
There are two levels of teamwork one can encounter when making a game- collaboration, where your teammates are fully interacting with you in developing the game, and outsourcing, where you bring in an outside person and have them complete a task with minimal interaction. For the most part, you will encounter collaboration. However, with things like music, sound effects, extra art, and releases, you will often find a "third-party" individual or group performing the task with minimal involvement with the development, sometimes that individual never even seeing the game until the final release.
The Cast of the Play
Every game needs certain people performing certain tasks. Below are the tasks that must be performed, listed by the usual name for the person who performs that task (note that these names/titles change depending on how the game is being developed and a number of other standards). Note that in many cases, tasks are combined or shared through multiple people. In the case of three or more people performing one task, one is often designated as the "Head ____" or "Lead ___" for the project, and has administrative powers over those in that department.
Creative Lead/Project Director: The Creative Lead is responsible for the overall feel of the game as well as overseeing the development as a whole. Often times, he/she is also one of the writers, if not the writer, and is in charge of finding new members. He/she may be responsible for creating a website/webpage for the game, checking in with members of the team to make sure things are on time, developing early concept work for the game (or working closely with the concept artist(s) who do, organizing the schedule for development, making decisions on game elements, and the selection and removal of members.
Programmer/Coder: The Programmer is in charge of creating the scripts for the game. In the case of Construct 2 games, he will most likely be the person with the main game files (unless the team decides to use a dropbox, but more on that later), and also will not need to make an engine for the game, as that is given. He/she MUST have a solid understanding of how to use Construct's scripting system (or if using another engine or building from scratch, the language that engine/programming language uses). The Programmer will be in charge of coding new features, implementing the work of others into the game environment, creating tests for Alpha and Beta testing, and advising the team on what is and is not feasible to add.
Artist: The Artist creates the graphics for the game. In addition, there might also be a concept artist(s) who do quick sketches and mock-ups of game graphics to assist the Creative Lead visualize the game. Artists are generally skilled animators, and often have a certain medium they work in. Mediums include Pixel Art, 3D Rendered Art, Hand-Drawn Art, and Vector Art. Note that it is wise to have artists that all work in the same medium and often times in the same program as well, so that the game has continuity between art. Sometimes there are also different artists to create the HUD (Heads Up Display)/UI (User Interface) of the game.
Composer/Musician: The Composer creates the musical score for the game. His/her job is to write original music that fits the mood of the game, loops cleanly where it needs to loop, and is compressed to a good degree to not cause too much file size issues or too low fidelity. In addition, many composers also assist with sound design, creating or finding sound effects for the game. If you can find a composer that does both, you are well off. Note that MOST composers, especially ones that have been in the industry for any considerable time, are not willing to work on a project for free if it is long, especially if it is barely in development. Composers generally are hired as a third party near the end of the production, however, many young composers are willing to work for free, and even some veteran composers will do music for free if your game is either non-commercial and small, or work for a royalty (more on that later).
Tester: Once you finish your game in its basic form, you will want someone who has never heard of the game before to test it out. This is because they will be able to identify issues with the game such as plot breaks or annoying inputs or such that you never would have thought of since you are familiar with the game.
These departments together create an effective game development.
Note that the Music dept. noted on this diagram also includes sound effects
Ratios
When you are ready to put your team together, consider these ratios compared to the size of your production...
• 1 Creative Lead +...
For a small production...
• 1 Artist
• 1 Programmer
• 1 Composer (or use free tracks from online)
• 2 Testers
For a medium production...
• 2 Artists
• 1 Programmer
• 1 Composer
• 3 Testers
For a large production...
• 4 Artists
• 2-3 Programmers
• 2 Composers
• 5 Testers
Generally you don't need many composers, and programmers tend to want to work alone (as they work with much larger magnitudes of work, it can be hard to make clear how things work, and if neither understands exactly what the other did, their actions can lead to lacking optimization and issues in the game). However, art can be a bear of a task and it's good to have multiple artists. Regarding composers, you generally won't want more than one unless you have over 15 minutes of audio planned (estimate a looped track at 1-3 minutes and a title track at 3-4 minutes). However, you may need to have a composer and a sound manager who will do the sound effects.
The Idea
Not all games are big enough idea-wise to require a team to develop them. Be sure your game really needs all those people you want to get onboard! Remember that the larger your team gets, the larger the task of managing and holding it all together will get. There's a golden number at around a dozen where it becomes very hard for one person to oversee everything. If you figure your game needs more than 6 people, it's probably too big for you unless you have already made several games yourself already. One of the other key problems with group games is ones that are simply too big, or that the game idea is too big to be made by a group (examples including things like clones of existing professional games, MMOs/MMORPGs, RTS, etc.). If you haven't read it already, the article "Why Your Game Idea Sucks" explains this well enough.
Prepare your idea, get some concept work together, and write down as much as you can before you seek team members. A prototype of the game is also very helpful.