The "Ultimate" striker has the following things:
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Very high ASI UV's on their weapons. Striker booster gives ASI medium, making it a max without trinkets.
Very high damage bonus from their Skolver armor. Striker booster gives medium, making it a max without trinkets.
A max UV on their armor, either Shock, Pierce, Shadow or normal.
Two Tetra Heart Pendants or higher.
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Damage isn't a good skill indicator. Besides how skilled you are, it's dependent on how long you spend fighting. Heart pendant users have more durability and can spend more time doing damage. You could get a good score by singling out the newbie strikers on the other team while ignoring the guardians that are capping points, that won't make you skilled. Some general tips:
* Instead of doing the full Final Flourish combo, dash up to someone, hit once and then move again. Shield canceling the first hit is very effective and won't leave you open like the last hit of the combo. This is a good way to win against other striker who like to auto-target + combo a lot.
* Instead use the combo to escape situations. If you're cornered, without charge use the final flourish combo to move you past your enemies and hopefully out of harms-way. This only works if you don't use auto-target. Speaking of that-
* You can enable auto-target with left shift (default I think). I like Auto target on my Flourish, but on the Faust it might make the difference in hitting all members of a group or just one who's slightly to the left.
* Every special move relies on your charge bar. Even in big fights, try to let your charge bar recharge. It takes some discipline and practice, but start just walking around a bit. You'll be the least prioritized target and with a bit of luck you can restart the fight with full charge. With some experience you can find a safe place to maybe take some pot-shots while waiting.

For Guardians, unless you have heart trinkets you have to take your time to pick them apart. The first thing is breaking their shield, which the GF is best at. At max damage bonus, two hits should be enough.

# You can try hitting them once from as far as your range allows (find the very edge of your GF and FF hit ranges) then retreating again. You can do that after standing still and staring them down for a second, which usually confuses them a bit, unsure what to do since they usually counterattack and you're not attacking.
# If they like to combo, feint a charge and watch them combo the air. Hit them with a GF when they recover from the last hit. You'll see the best guardians use a pierce blade and only hit once, but always whenever you get in range.
# Ring around the guardian works only if you have decent latency, max ASI and is less likely to work if the guardian uses auto-target. You walk to just outside of his range, then quickly dash behind them. You hit once (just once) and dash behind them when they turn. Repeat that as chaotically as possible, sometimes going a quarter instead of half circle. Only do this with full health and be careful against the sealed sword line since the second hit has an extremely wide arc.
# Another very effective method is weapon heckling. You shoot with a Polaris so they either begin to focus on dodging or start shooting back. Then dash in and hit them once, get back out of range and start shooting again. This confuses them, and you can kill them without breaking their shield. If they start simply tanking the hits their shield won't last long.
# You can use the slowness of Polaris shots by firing them from some range, then dashing in to attack his shield. If he counterattacks and makes you flinch, he'll get interrupted himself by your Polaris shot. I use this near the base because it usually means you'll take a hit, but it stops you from getting instantly killed by a full GF combo.
# Simply Polaris them to death. It takes ages, but without striker/recon backup you'll eventually take them down.
# Make them fight on a haze bomb. Tricky to set up, but charge a bomb (stagger storm/Voltaic tempest) and set it near them. Unless they want to give up the point/have a fast firing gun they'll have a dilemma that most will solve by shielding. Simply keep putting down bombs, they can't move and will usually drop it and try to run.

damage is a good indicator provided the game doesnt have any more than one noob in it. and the person who did the massive damage also capped alot. also +1 on tennis' guardian strategy. i see too many people trying to rush around the backside of guardians. you can do everything you need while dancing right in front of them.