Sounds like an interesting topic
I haven’t played many rengo online so far and I tend to place a lot less importance on online games so what I’m about to say is based on my experience in irl pair go tournaments. In these, I have always played with a stronger teammate.
The tournaments in Italy we always won without too many problems, being weaker than my teammate didn’t weigh too much on me even when I realized I was making mistakes because I saw that all the other women were weaker😅
(it’s a bit sexist reasoning, it doesn’t make sense to compare myself only with women)
In the international tournaments I did, however, it was different: we were always one of the weaker pairs and we lost often. My teammates didn’t have high expectations on me but I felt very guilty when we lost and I played a lot of ko threats during the games for fear of making a (worse than losing one ko threath) mistake.
So, I would say that how you feel also depends on the result and the opponents. For me (and I think not only for me) a defeat weighs more if I feel that I am making another person “suffer” as well. I usually don’t care about individual defeats, but if another person is involved I feel a bit guilty.
I have no experience of being the strongest player, but I imagine it is very difficult and sometimes frustrating. You have to try to play simple things because (usually) you can’t rely on the other person’s reading.
Actually I think the level doesn’t matter much because two players with the same level can have very different characteristics. For example, a 5k may know very well a lot of joseki that another 5k misses, or their reading ability may be very different. A team is stronger if the players have similar characteristics.
One thing I found very frustrating once was that my teammate was too slow and we would lose some games due to time. Pair go tournaments use absolute time. I usually play very fast. It shouldn’t have mattered to me. Hopefully I’ll become able to overlook these things.
I have never had a stable pair go partner. I have played 8 tournaments (I think) with 7 different teammates. Some of the best European pairs (e.g. Kovaleva - Surin, Cao - Fenech, Kralikova - Jadron, probably someone else as well) are steady and I guess having a stable pair go partner to train with is good to learn how the other plays, but I haven’t found anyone really interested yet.
It’s more about pair go than rengo in general, but at least it’s something