Interceptions have mostly been with SU-27s with some SU-35s patrolling as well. They often have AWACS up, but unlike the West they are rarely seen on ADS-B or similar - partly because they are actually being utilised in active combat missions.
The S-300 and 400 systems are a bit of a wildcard as they rarely have them properly spun up for a variety of reasons and there are complications with doing so but they are capable systems as well as capable of going spectacularly wrong. If Ukraine did start pushing offensively they'd almost certainly have to bring those systems fully online and move up more Pantsir, etc. systems.