I think it’s better to do Cryo1 if you want to support your friend, if you want to deal then keep Pyro but I doubt you will have enough dps “late” game.
I’m not a “pro” Linker so idk for Joint Penalty but I made a build if you want to take a look.
Noobexperiment9999 : For Wiz it’s like you want (for the dps skills, but Lethargy at 1 + the passive if your friend take some skills with Strike atk)
For Cryo I think there is not so much choices…
Linker is more optimized like that (I think! Really know nothing about this class except reading and look the videos about the skill)
Thauma is like you want (Swell left arm lvl max and at least 1point in Transpose)
Chrono, Quicken maxed, coz your friend will AA a lot (I think) and you too (when your skill will be on cd), haste maxed, Slow dont need more (for me). The rest depend of your style.