I am looking at the Advanced Player's Guide, and I see that they have Teamwork feats. These are interesting, but I don't see them being used by PCs very much.
What I am thinking of doing is making a Teamwork Skill (key ability: Charisma). If you make a DC 20 roll using Teamwork, you can use any of the Teamwork feats that apply, providing you have the prerequisites for the feat, and your partner makes a DC 10 roll. You have to be able to communicate with your partner. You can only use one feat in one round, unless both you and your partner are affected with a spell that grants an additional action, in which case you can use as many additional feats as you have additional actions.
I'm not sure if I picked good numbers for the DCs. Perhaps the target numbers should depend on the feat being applied and what the PC is trying to do.
The effect is that nobody "takes" a Teamwork Feat. The Teamwork Skill can be used untrained, but the DC 20 is hard to meet without having ranks in the skill.
I'd have to decide which classes have this as a class skill. From the Core book, probably Bards, Clerics, Fighters, Monks, Paladins, Rogues, and Wizards. From the Advanced book, probably Cavaliers and Witches. The Gunslinger would probably also have this as a class skill, since in my setting many of them would be trained as "musketeers" or "dragoons".
(I don't have plans to use any of the other classes currently in playtest, so I haven't considered if they would be likely to have this as a class skill.)
This is just something I thought up at 2 in the morning. I think this approach fits the style of story I am thinking of, in which panache and teamwork is emphasized. (The specific campaign I am considering is set in the 17th Century and inspired by the Three Musketeers.) I welcome any comments and considerations.
The Knowledge (tactics) skill I was thinking should be part of the game would work great with this idea. Probably could work as simply a general "Tactics" skill that's also used for knowledge-based stuff.
The only thing I'm not sure about is the partner needing the DC 10 check.
This skill makes sense as a Charisma skill if it lets you direct an ally to assist you in getting this bonus. However, the ally now has to make a 'charisma based skill check' to do the thing you directed him to do?
Honestly, if only the person making the skill check gets the bonus, then it should be enough that he meets the check and you have an ally in the qualifying position.
Then you can have feats that grant a higher bonus to a specific teamwork effect, or a feat/class ability that lets you give your ally the benefit as well, or for those that don't want to invest in the skill and want to be good at that one trick, there's the old style feats.
Nice idea!
The reason for both people having to make a check is to mirror the APG concept that both allies have to have the feat. If your ally is on the ball, it works, but if she is distracted or not aware of what you are trying to accomplish, it might now work.
I'm thinking perhaps the person trying to start the maneuver would make the check to see if he could get all the ducks lined up to do so, the maneuver starts, and then the ally makes the check to see if the stunt works. If the ally succeeds, it works. If she fails, the stunt does not work. If she fails miserable (adjusted roll of 5 or less), the stunt fumbles.
For example, you want to use Allied Spellcaster to get your spell to get your spell to overcome a demon's spell resistance. You roll a 22 on your check, so you can try to draw on your ally's power. If your ally rolls a 12 on her check, you get the +2 or +4 bonus. If she rolls a 9, you don't get the bonus. If she rolls a 2 (silly ally), then you take a penalty because of the time you wasted trying to get her attention to assist you.