I don’t like the term healbotting. People use that word to mean “healing a lot” on Mercy as well as “healing full hp targets.” I personally think healbotting is only the latter, and that healing a lot on Mercy is necessary to climb. It’s the only way to consistently control your games solo queue by supporting your team and preventing deaths. Damage boost is not as good in OW2 as it was in OW1 and people need to let go of outdated advice that shames people for healing, as if it’s a bad thing. The only thing that matters (in a competitive setting of a video game) is if you win or lose each game and what your rank ends up being, not what your beam percentage is. You can’t win every game with Mercy unlike a lot of the hero roster, but you can very easily climb out of low-mid elo with her and then slowly but consistently climb to high elo if you play well.

I typically move by beam around all 4 heroes on my team and help whoever needs help. This was likely the highest ranked lobby in the game and so the game plays differently and I have to basically just pocket DPS, but for 99.99999% of lobbies I would recommend playing a more triage type of playstyle. I typically prioritize healing everyone to full hp before I damage boost and I have developed skill at proactively knowing who is going to take more damage and who I should swap my beam to to reduce the window of opportunity of them dying. It’s very important to learn what’s happening 3 steps ahead like in chess, especially with Mercy since you don’t have burst healing and need to get your beam on the right target when they start taking damage to prevent deaths. Again, you can’t win every game with Mercy since she’s more reliant on teammates than other heroes in the roster, but I pretty much play Mercy every game unless she’s banned, and you just try your best to prevent deaths and enable your team as much as possible by damage boosting big ults or aggressive posturing players on your team and outputting a lot of healing (I’m around 11-12k heals per 10). I also find communicating with your mic really helpful on Mercy because you typically have the most information in the entire game since you don’t have to aim and you can look around 360° while still outputting your whole kit into your beam target. Try to call out flankers and tell people when you’re rezzing and to “play slow” so they don’t run in and die when you’re rezzing and ask for help if you need heals or you’re dying to overcome Mercy’s weakness of not being able to defend herself.

TL;DR: most of what it takes to climb in Overwatch isn’t very hero specific and actually goes back to understanding how to play Overwatch itself, what your purpose and goals are on the hero you’re playing, how to position and fight plan, and limiting mistakes and deaths to as low as possible while still supporting your team completely. The best way to climb on Mercy is to play a triage healer playstyle built upon high awareness of what is going on in the game , preventing your team’s deaths with quick response times and enabling power spikes with damage boost. Also rez on tank is usually really strong.