Only way for them to team up in canon is for Grogar to raise Chrysalis and Sombra's spirits from Tartarus. If my below-mentioned theory is correct he could do the same for Tirek, but despite this all I'm not sure that was what they were going for with Tirek and it was meant to be more of a standard reimprisonment so probably not Tirek, but I could see Grogar raising Chrysalis and Sombra as ghosts



Still this makes a good fanfic