Hey everyone. Been posting this guide in a few threads for people looking for a good Fire Main lineup, so I figured I'd just post it here and let everyone have a look. Currently Rank 6 for power on Server 22: Jiraiya (after a ton of hard work and 90+ straight 100% completion days...), and I'm staying competitive with the rest of my server in every event.
This is the lineup I've been using since I got regular Kankuro to 3 stars, and the only update was changing it to the GNW Kankuro when he was the reward last month, but that's not a mandatory one. If you only have the regular Kankuro, the lineup works just as well.


Overall this team has been fantastic, and it's allowed me to hold my own against cash players using Sage Naruto+Iruka lineups, or Pain lineups, with relative ease, simply because of how strong Hinata is at interrupting their ability to combo, and clutch main character Sleep/ULT to lock out an entire turn for a key character.
Characters
Tobi
If you're a F2P-er trying to be competitive, do yourself a favour and start using your Survival coins to get Tobi ASAP. His resurrect ability and incredible chase damage (plus two Ignite hits) are a clutch reason why this can stay so competitive against Earth shield tanks and characters hiding behind clone walls. Not to mention the chance he has to straight up dodge an ULT every turn.
Hinata
As we all know, Hinata is one of the pride and joys of F2P users for the incredible amount of damage she can tank, and her double chase + Acupuncture abilities. Easily one of my favourite characters in the game, and I'll be sad to see her go as I get to higher levels and (hopefully) get some lucky Treasure pulls.
GNW Kankuro / Kankuro
One of the stronger auto-combo ninjas, given the status effects he inflicts and his ability to block damage & status effects from hitting your other characters. Poisoning and ignite are huge factors in allowing this team to combo-kill opponents off of a single ULT ability.
Strategy
The overarching strategy of this team is the same as most F2P Fire mains: Don't get to the late game.
Other than that, it just takes experience knowing when to use abilities, when to hold off, and watching initiative order to determine if you can get the jump and interrupt opposing combos.
First Round:
First things first, you're going to want to use Hinata's ULT first turn almost every game, as you need to have some way to absorb early damage and prevent status effects from hitting the other key players. This is especially true against Lightning mains who will try to shotgun down your team with Lightning Armor on Turn 1.
Immobile from your main character is a little more flexible, but again, typically you'll want to use that first round unless you look at your opponent's lineup and know for a fact that they're going to use their third/fourth character's ability next turn, so you can jump in and negate it. Just remember that you need to be watching to see if your initiative allows you to go before their 3rd slot, so your ULT doesn't get wasted by countering nothing.
One key thing some players also don't realize: Immobile affects the targeted character during their NEXT turn in the initiative order. So if a ninja has already moved, casting Immobile on them will negate their entire next round of actions; and that's a huge detail to know to play this lineup properly. You need to be able to look at your opponent's team and determine if there's a key character you need to lock out on turn 1 or turn 2, and arena is a great way to learn how to do that, as you'll go against all kinds of lineups at varying power levels.
Second Round:
Completely depends on if your Tobi acts first in the initiative order and if your opponent has a large combo set to go off which you need to interrupt. And I have to stress the word need. You want to make sure that you only use Tobi's ULT as a countermeasure against an enemy combo that you can't afford to get hit by.
If they are simply going for a damage combo and you expect your character to live, hold off on Tobi's ULT, and use Kankuro to hit the entire team with damage and Ignite+Poison, as the extra damage will be very important in allowing your combo to kill characters in one shot.
By the end of the second round, you should have been able to focus fire down at least one character, and winning will just be a matter of negating abilities and sleep-locking the top lane with Tobi + Scarlet Blaze.
Hope this helps any mid-level Fire mains in need of a boost to get through Sage World and Fighting Matsuri.
Keep up the good fight F2P-ers!