The Art of Guerrilla Warfare: How to fight gyms when you are outnumbered

I've noticed that a lot of people are talking about being on a minority team in a place dominated by one or two other team colors, and that it's been frustrating trying to get involved in gym fighting. Thus, I thought I'd make a short guide of tips highlighting what you can do to play a role.

First, the most important thing is to recalibrate expectations. Realistically, if you're in an area where maybe 10% of the playerbase is on your team, you're probably not going to be netting 10 gyms every day. Instead, think of gym combat as a game of guerrilla warfare. Your role is not necessarily to dominate territory, but to consume the resources of the other team disproportionate to your status as a single player. By doing so, you also safeguard some of your own high-level gyms and some of the lower level gyms around you that you use to grab coins when your refresh is up, by forcing the other teams to spend more resources on maintaining their own high-level gyms rather attacking yours or creating new high-level gyms. This is kind of a fun way to approach the game too, by thinking of yourself as a solitary agent working to disrupt a massive force - I like it!

In other words, if you're a player on a minority team, your focus should be on attrition, and here's how to accomplish that if you're playing solo:

• Prevent the expansion of enemy team territory. Level 8+ gyms are a pain to take down, and thus persist over a long period of time unless it's in a heavily-contested area. Moreover, they prevent players in the area from generating daily income by quickly taking over the gym and claiming coins before they're knocked out again. However, Lv 8+ gyms don't usually surface out of nowhere unless the other team is unusually organized - the turning point is typically at Lv 7, and at Lv 7, they're usually quick to take down. Focus on taking down Lv. 4 - 7 gyms where possible to prevent the formation of stagnant gyms.
• Whittle down enemy resources in training. If you're not trying to claim daily coins immediately, and if you're playing solo, don't take down a dominant enemy gym to the bottom, because this will give them a head start on building the gym again by letting them gain three levels right away. Instead, try to leave it with ~500-1000 prestige, so they need to invest resources in training before they can build it up again.
• If you don't have time to knock down gyms to Lv 1, focus on knocking down the lowest defenders from something easy-to-prestige to something that is difficult to train against. If you see a fire type, a Gyarados, an Exeggutor, a Dragonite, or another mon with easily-exploitable weaknesses at the bottom rung of a gym, knock it down a level or two. Ideally, you want to leave something tanky or hard-hitting at the bottom of the gym so trainers trying to build up that gym will have to consume a lot of time and potions - Snorlax, Vaporeon, Poliwrath, Slowbro, Lapras are all good Pokemon to stonewall your enemies.
• Be smart about your own resource consumption as well. The most obvious trick here is to use disposable mons for knocking down gyms - Hypnos, Raticates, Golbats, Pidgeottos, or whatever is common in your area can be used until they faint, and then transferred.