So you've always been curious about that Combat Medic (CM for short) Talent Pip has. People don't tend to rave about it, often ignoring it for the already-unlocked-by-default Mega Potion (MP for short) talent. This is in part due to MP being fairly potent; 2000 near-burst healing in one throw is nothing to sneeze at, especially with cards that make you able to use the potion more often when you hit allies. CM by comparison does 700 per shot (4200 for a full clip), which sounds like a lot less if you only heal with your potion launcher, However, many people forget (intentionally or unintentionally) you still have a 1000hp potion to use! which of course, also takes advantage of any loadout card Mega Potion can use. I call this a hybrid style of play, and I've found it to be far more effective than solely relying on either MP or CM by themselves.
MP is limited by the healing per second (cards have internal cooldowns, so you can't abuse the "Reload" loadout card constantly), but it does do a lot of healing in that short time (up to 4000hp within a few seconds), but again, cooldowns are a factor, and Chronos can only do so much to alleviate this issue. However with CM, you're free to keep healing whoever's in front of you until you need to reload. And when you're reloading, you can just throw out a healing potion, reload, then throw out another healing potion, and then keep shooting and healing again, and so on, and so forth. So CM does have its advantages, if you're willing to work for it.
Added during Radiant Stars was the CM-specific quirk of knockback being removed from the potion launcher while shooting, and shots no longer damaging you. The latter was especially problematic when you were healing up close when your potions were on cooldown (as you might imagine, this is completely antithetical to the playstyle as it damaged you while you try to heal your allies). Despite the upsides, there are people out there that consider this change to be a nerf, on the grounds that it removes knockback-jumping. Knockback Jumping is basically the Diet Cola Lite version of Rocket Jumping, only less useful in every possible way. It's a seldom-used technique that lets you get to slightly-out-of-reach spots on maps. Not only does this technique require knowing how to pull it off (which requires practice, and yes, does technically raise his skill ceiling), but you've gotta know where you can do pull this off too, which isn't in as many places as you'd think, as it won't help you with jumping on top of the tall architecture Pip will never reach, regardless of technique. Our fluffy boi is already able to get on top of pretty much any mid-ground on a map anyway. So Knockback jumping isn't that helpful, and the benefits of not being damaged for healing someone severely outweighs the downside of using a niche flanking technique on a playstyle that isn't trying to get ahead of the enemy, you're aiming for Line of Sight, which restricts where you can move to anyway. This leads me nicely into how to move as a CM Pip.
The best way of describing positioning of Pip with Combat Medic is this: Reverse Flank. Don't stay in one place for very long, always keep moving, but always in line of sight of your frontline and other players so you can heal them. Be hard to track down, climb high up and heal, get back down and heal, just be hard to pin down. Heal anyone and everyone in front of you, your range is only limited by Pip's (very long) arc for his launcher and his (also very long) potion arc, and anyone who gets healed even 1HP by your potion will contribute to the cooldown reductions the below loadout uses. In an ideal situation, in about 5.5 seconds, you can heal 4100hp (one potion, three shots, then another potion), reload, then an additional 3500hp on top of that while your cooldowns are still off (5 shots of 700hp). In reality, the numbers are likely going to be fudged due to cauterize and, well, you're not entirely a robot, so about 4000hp - 6000hp within about eleven seconds is probably more accurate a guess (again, cauterize will make the number go down).
Oh, and don't try and fight 1V1's... you'll likely not win them. Your kit has been made to heal more than harm. You're basically a healbot, but that's part of the playstyle; maximum healing attention for decent results. I personally like the effort, as it feels like i'm helping (maybe i'm just dumb), But i'm not against making CM have more healing (700 -> 850hp per shot)
So the cards I've chosen generally lend themselves to the hybrid style of play I talk about above.
Increase the radius of Healing Potion by 24%.
Heal yourself for 60% of Healing Potion's effect if you hit an ally but not yourself.
Reduce the Cooldown of Healing Potion by 3s for each ally it hits.
Reduce the Cooldown of Healing Potion by 0.30000000000000004s after hitting an enemy with your weapon.
Increase your jump speed by an additonal 10% while using Weightless.
Potion Launcher also Heals allies hit for 700. You no longer take damage from your weapon shots.
Medicinal Excellence (Level 3)
Using this card guarantees the already large hitbox for your healing potion to hit more people. Your aim is to hit as many people as possible with the potions, so this helps out with that.
Gift Giver (Level 3)
This is largely for your own survival, after all, there's no point trying to heal without some self healing mid-battle, and wasting a potion on yourself is just not going to be fair on your allies. Level 3 gives you 60% of the healing (600hp ideally, pre-cauterize), which is gonna help you with the self sustain a bit. Might save your life too.
Reload (Level 5)
As with Mega Potion, this is the
downstairs living room most important card in your loadout. Your healing potion, before Chronos, has an 8 second cooldown, so hitting at least 2 people with it will shave six seconds off the cooldown, and hitting more is ideally something you should aim for, and will get your healing potion off cooldown immediately. The internal cooldown for "Reload" is 5 seconds, meaning it can't be abused too much, so keep an eye on it. There is a HUD option to enable card cooldown timers so you can keep an eye on things.
Acrobat's Trick (Level 3)
This is an interesting card, and one I've chosen it for cases where you want to weaken enemies at mid-range, and it'll lower the cooldown of your healing potion (by 0.3 seconds in this case, which stacks until the cooldown is reset). You shouldn't rely solely on this card to reduce cooldowns, that's not the idea, It's here to keep cooldowns low while reducing risk of you dying.
Sprint (Level 1)
Just increases jump speed. You can probably replace this with Escape Artist if you want. Pip can Z-Jump (wall jump) pretty far and high, so this helps with movement speed a bit.
When it comes to what items in-game to use, the most important items are: Chronos (speeds up cooldowns), Haven (reduces direct damage taken) and Deft Hands (speeds up the reload of potion launcher).
Reduce the Cooldown of all your abilities by 10%.
Reduce the Damage you take from Direct attacks by 7%.
Increase your Reload Speed by 40%.
Reduce the Cooldown of all your abilities by 20%.
Increase your Reload Speed by 60%.
Reduce the Damage you take from Direct attacks by 14%.
Reduce the Cooldown of all your abilities by 30%.
Reduce the Damage you take from Direct attacks by 21%.
Deft hands isn't very useful in the early rounds, as item credits are better spent on cooldown reduction on your healing potion.
Chronos 1: This will help early-game, where your focus should be on just healing as much as you can.
Haven 1: Nice to have starting off with.
This is where things get more serious, and where enemies also start to take longer to kill and thus, you need to heal for more for longer. a 40% increase in reload speed will do you fine to start off with, and Haven 2 will keep you from getting too badly hurt. Chronos 2 should be purchases soon after just to keep cooldown times low.
Deft Hands 2: Immediately upgrade to Deft Hands 2, as this is where it gets important to minimize downtime between reloads.
Haven 2: You'll have a lot of people trying to kill you at the best of times, but now people will really start to hunt you down. This'll help you stay alive.
Chronos 2: If you can, buy this as quickly as possible after purchasing Deft Hands.
Deft Hands 3: Makes you reload very quickly. Pip has now entered maximum speed.
The cooldowns should now be as low as possible to make healing faster to give to allies, as well as max damage resistance to keep you from being bursted down too easily.
Chronos 3: Maximum cooldown reductions are at play now.
Haven 3: 21% damage reduction is now at play now, which again, will keep you alive.
Other items to get are Bulldozer or Wrecker (1/ 2, as 3 isn't worth the credits and are better spent on other things). Cauterize isn't helpful here as you won't be killing enemies that much, only scoring Eliminations at a push, so don't go out of your way to kill people, let the frontlines and damage sort them out. If you get into trouble, shoot an explosive flask their way to slow them down, and run for your life towards anyone who's better equipped to help you.