Infiltrator chandy is pretty meh. Nabbing that flash fire boostand that immunity is really good. i suppose ypu could use it as a check to espeon behind a sub. Esepon is so frail tbh that its pretty easy to check. A better option imo is infiltrator crobat, which hits espeons weaker defense stat while hitting behind the sub. It is one of the other faster infiltrator as well so it doesnt have to worry about taking a hit. Another good option is noivern.
Regarding your physical vs. Special king question, special or mixed with superpower is bybfar the most superior. With mew gone, the mega aggron/florges core is much weaker, but mega aggron can handle physical nido with earthquake easily and rk with little ease. Its almost cleanly OHKO by earth power though. But, blissey is the premier special wall of UU now, but it is maimed by a LO superpower expecting a sludge wave or earth power. Physical king is also prone tobWoW now, which makes its job harder. Immune to toxic and thunder wave and no need to worry about burn is another plus for special nido.
While kings attack is better. The BP of Sheer Force boosted moves is greater on average. So, a dedicated special or mixed set is the most viable (moreso if you choose superpower/sludge wavs/earth power/ice beam)