Min/Max effective level for Medium Bot/Weapon?

4/6 i think is border for mediums before heavies predominantly take over

This is my experience as well. I'm often top damage with 4/8 mediums often facing leos, griffs and tashas. Occasionally see a galahad or rhino and even a lancelot once.
Most of the heavies at this tier will have level 3-6 weapons, so level 8 weapons on the mediums compete very well.

So I just upgraded a few of my medium bots to level 5. Is this going to push me into a higher tier? My only heavy bot now is a level 6 griffin.

Weapon levels matter as well... Bot levels are only part of the equation.  What is the highest bot level and weapon level in your hanger?  (As it stands... the strongest bot/build determines your matches.

I think for heavys the highest for silver is 4/6, can someone confirm this?

I run a pair of 1/9 lights with three 4/6 mediums and the following is true:

Leos, Griffs and Natashas are really common
Stalkers are fairly common
Fujins and Raijins are seen at least every other battle, sometimes multiples in a single battle
Gareths and Carnages are uncommon, but occasionally seen
Lancelots and Rhinos are fairly rare catching me a bit off guard when I've run into them
Furys are white whales

Admittedly I'm not very skilled at this game and I still don't get how the tiers work. I should be high bronze, yes? So, why so many WSP bots? Shouldn't they be silver only?

From my experience, all the talk about tiers is just player shorthand for what seems to me a very fluid system (or maybe just one for which the exact parameters still elude us). There are others who have much more time spent analyzing the matchmaker than me, so this is just one player's impression after a few months of playing and reading various threads on the topic. The way I find it most helpful to think about it is that the tier designation gives you a rough approximation based on your strongest bot of what level of competition you are most likely to see. However, there are obviously other things at play besides a strict top bot score. For instance, some people have talked about specific levels of weapons bumping you up, even if your averages are still within what is assumed to be a specific tier. I believe I've seen this myself. When running my hangar of 2/5 lights, I upgraded one wep on one destrier to level 6 (the other was level 4, so it should have still been considered 2/5). I immediately started seeing high-bronze even low silver level of competition. Suddenly I was seeing half the enemy team be 6/3 and 6/4, even 6/5 heavies in every match. When I swapped out that level 6 weapon for a level 4, so no weapons in my hangar were above 5, the competition was back to the normal mid-bronze lights and mediums that I am used to with that hangar. Could have been just a fluke of the available matches at the time I was playing. Or maybe it was that level 6 weapon.

Maybe your level 10 weapons are bumping you up or something like that?

Dasveen, if the upper limit on high bronze is 4/6 mediums, both of your Boas (just barely) exceed them, being 4/6.5 each.

Just as an FYI - I ran them at 6/6 for a while and when I bumped one to 6/7 I ran that for a while. By a while I mean multiple days, so as to understand the real impact (some have noticed that the MM doesn't always pick up hanger changes immediately). There was 0 difference in the competition I faced. It just got a little easier to take another bot down.

In fact every change I make is done with an item from inventory, so I can back it out. When I first moved my Boas from 1 to 2 there was an immediate difference, so I backed it out and make a couple of other changes first. Also, moving my Boas from 2 to 4 didn't seem to make any difference in my opponents either. Basically moving my Boas from a 2/6/6 status to a 4/6/7 status brought my win rate up, as my competition remained the same, but my bots had noticably more structure, speed, and a smidge more damage.

So, yeah, technically 6.5, but so far, at least for me, .x weapon variations haven't made a difference. I expect a change at 4/7/7 for my Boas, but not sure if 5/6/7 would make any difference. I haven't decided if I want to test it, or wait a bit for some other items not in use that are being leveled and roll out my new bots (I've got enough for another WSP bot and 5500+ Au burning in my pocket).