I’m convinced nobody know for sure exactly how PvP matchmaking works (even the devs, at this point).
There have been many, many anecdotal reports that using a lower score defense team will lower the score of the average team you are offered in matchmaking. Official Dev word is that defense team has no effect, and your average invade team strength over time is what determines your matchmaking, along with your current PvP rank. Based on what I’ve seen, I’m more included to believe the former rather than the latter, but even that is sketchy. There have to be more factors at play. I know for a fact I’ve seen three offers of <5k score on my completely maxed out account, while often seeing 8k-9k+ on my low level account is pretty suspect otherwise.
For what I have observed, any bonus that affects your score (gaining hero levels, leveling a kingdom to 10) also affects your matchmaking. Bare minimum, this changes how much gold you are offered for a team of a given strength. Stuff that was “above” or “equal” your maximum potential score gives less gold, while stuff “below” your maximum potential score gives more gold. As your global score bonuses rise, your average offered matchmaking will rise with it. I’ve noticed that every hero level below level 1000 adds a bit to your score, regardless if you use your hero and regardless if they get any skill points - presumably from the mastery points, but mastery points from other sources don’t add to your score, so as far as matchmaking goes, leveling is still “bad”.
If matchmaking is by maximum team score potential, by the way, traits hurt you a lot more than having a single level 20 mythic in this regard, because they often add a ton of score to your team. Any troop of a given current rarity (regardless of current rarity) and a certain number of troops in a team of a certain size will always add the same amount of score. A single fully traited troop in any team versus one that has no traits, if they are equal level, is a 450 point difference regardless of their base or current rarity or your level. First traits add 50 points, second traits add 150 points, and third traits add 250 points. The difference in score between a fully traited team and an untraited one is 1800 points, which is more than the difference in score between two teams of equal traits but one having unlocked every bonus including guild bonuses and one that has no guild bonuses and only a few five star kingdoms. The difference is score between a level 19 legendary and level 20 mythic, with every single bonus unlocked, is only 70 points. And over half of that is just the troop being currently of mythic rarity on top of that.
If the whole “maximum team score potential” is to be believed, fully traiting anything that you have four copies of and have fully leveled will automatically put your “score potential” at 1800 points higher, because you could technically make a team with four of that one troop. All things being equal, you’d probably get more score out of, for example, a fully traited Soothsayer at level 17 or 18 than your level 20 untraited Pharos-Ra for any given team. Even if the rest of the team is three more Soothsayers. It would actually be kind of laughable if it does actually works this way, as fully traiting any low rarity troop would have this same effect.
All that being said, I wouldn’t worry too much about leveling or traiting stuff. I’ve been unable to confirm the whole “maximum team potential” thing one way or the other. Based on what I’ve seen, only your global score modifiers (hero level, kingdom bonuses, guild bonuses) strongly affect this, and even then, the matches you are offered are heavily random.
In my experience, if you are low level will get a ton of matches that are much stronger than you as the “hard”, and occasionally the “medium” placement. Regardless of what you do. Especially the rightmost match, which usually has a couple thousand points over even my “soothsayer brigade”.
All hope is not lost, though. Even without a “meta” team, you can build some low level teams that are quite effective.
On my side account, while I was extremely low level, I use this team to great effectiveness:
Dragon Eggs
Dragotaur
Dragonian Rogue (Dragonette if you dont have him, but D. Rogue is much better, maybe use Pharos Ra if you dont have D. Rogue)
Baby Dragon
The basic configuration is at least 3 dragons from Dragon’s Claw, one being Dragotaur, one being D. Rogue if you have it. Despite being a summoner, I put eggs up front here because he can usually stall one more skull hit while Dragotaur buffs up the team. Once you buff a couple times, you can usually finish anything off by matching skulls. D. Rogue hits from the rear and similarly can one-shot if you have enough purples in range of the spell. The team is most effective with at least Dragotaur and Dragonian Rogue, since they can bounce back and forth on casts due to their board destroy spells, usually only stopping to have to match an odd gem.
There are other configurations you can use with this. You can also use a crude club Warlord up front instead of Baby Dragon, moving eggs to the second slot. He won’t get buffs from the Dragotaur, but starts off hitting hard and lasts just as long as Eggs if you level the Warlord class. My preference is to use a Wight in the back for soul generation and to get more purple on the board for D. Rogue, a legendary dragon from another kingdom if you have one and can cover the colors, or something like Dryad instead of eggs toward the rear of your team. Due to the kingdom bonuses and massive buffs from Dragotaur, this team is capable of taking out stuff much stronger team, and on a budget - I still have this team set up in my first slot, and I still have Dragon Eggs at level 6, Rogue at 5, and Dragotaur at 15, with Wight only max leveled and traited so he can get more souls. You can unlock the “bond” traits if you want for a bit more survivablilty, and Wight’s traits are all good, but otherwise don’t bother.
This configuration might not work against the rightmost option when it decides to spit out teams with over three times your score, but I’ve found it is solid enough to take out the middle option, often while being at a score deficit of over 1500 points.
Though if you let me know what legendaries you do have, I may be able to help with a better team with Pharos Ra. Right now, I’m picturing something like Zombie, Giant Spider, Valk, Pharos-Ra. At low level PvP, that should be enough for him to one-shot, you have a summoner, and with the right set up, Pharos-Ra can take out half a team after minimal setup (charge valk > valk fills spider > spider fills Pharos > Pharos fills himself and clears off most the remaining gems). You’d want necromancy on the Zombie and Magic Link on the Spider and Water Link on Valk if possible, but the team should work with most of them at relatively low level since it works kind of like a loop. You can let the zombie die over taking skulls early on, the necromancy should still work.
FYI, if you are interested in using Rowanne, she is available at the end of the Forest of Thorns questline.
You took the time to write up a really nice summary on some of the better troops and try to help answer my question, so thank you very very much.