Yesss we totally agree, creating a damage calc for the teambuilder is definitely something we want to add in the future. Currently we're working on reading data from the teambuilder and inputting it into the damage calc (which will introduce some exciting new features in the next patch). After that, the biggest roadblock is really thinking out the UI/UX and how we want to lay everything out. Our initial idea is to create an improved version of the One vs All, All vs One modes from the PS damage calc. The idea is to make it quick to add sets and filter the list of mon you want to run calcs against, and then laying them all out in an easy to scan list so you can quickly check calcs against the metagame threats while you're building the team. We'd also have filtering options, so for example, you could choose to only see calcs for mon that are faster than you.This tool is wonderful for battling and I love it. One suggestion though, would it be possible to add a damage calc in the teambuilder that can sync during teambuilding? for example, if I put in a clodsire set in my teambuilder, that set automatically pops up in the hellodex on the right and then it is possible to change the opposing pokemon (like in the default showdown damage calc). This would be really helpful for those who likes to make calcs during teambuilding. Regardless, this an amazing tool wonderful job :D
Really the biggest thing is figuring out what players would want to see and use while teambuilding, like for example, I could see it being really useful to see a speed tier list that you can calc against, or other features that could help with setting the optimal EVs to live a certain attack from a certain mon. If you have any ideas, I'd love to hear them! We're still in the prototyping phase, and to be honest, it'll be a while before this gets released, as it's definitely going to require a lot of work! And not to mention, I think the PS damage calc still works really well and gets the job done, so we're not in a huge rush to get this released :)