I think that the Animorphs could have been much more effective in the war, with a different strategy. Seems to me that once the knowledge is widespread that this war is happening, the Yeerks would lose for sure. With everyone else keeping an eye out, the Controllers would be hard-pressed to get to their Yeerk pools, to hide the pools, to infest new people. Suspects could be quarantined for three days. Once their Yeerks die, the hosts would be able to tell all kinds of things about what the Yeerks are doing.
Seems like the invasion would be over in days.
Unless the Yeerks just used force and their spaceships. But it doesn't sound like that was something they were willing to do. They rely on stealth and building up numbers till it's too late.
So, strategy. Instead of spending their time and efforts foiling this Yeerk plan and that one, how should the Animorphs plan to get the word out? And do it in a way that people won't just think they're crazy?
A couple of ideas (maybe others will have more):
1) Try to get film footage of a Yeerk pool and people getting infested. Can they sneak back in as moles, and somehow bring a portable camera or such? Maybe Ax or Eric could help with something small that would really let them show infestation and everything.
2) Try to free someone really powerful. Instead of fighting hard to prevent the governor and such from being infested, you want him to get infested! Then wait a little while, and plan a kidnapping. Since the Yeerks kill escaped hosts, you need to do it suddenly and secretly, some time when no one is watching him. Break into his house, knock him out, get him far away before the Yeerks realize. Then tie him up for three days (or kidnap him just before the third day to save time). Once the governor is freed, he can come forward and tell everyone about the invasion, hopefully with video. Tell everyone that he doesn't know which policemen and doctors and all are infested, but we all have to on the lookout, and that in the next few days, a lot of infested people are going to be trying to cover up this story and say it's all a hoax. Tell everyone to go right now and find the underground pool in such-and-such a location. I think that, properly planned and a little luck, the story could quickly be impossible to squelch.