its a bit complicated to explain, stance is generally only good unexpected. MST mixups are very strong and RLC is decent defending and wakeup option, but its somewhat hard to set it up and you will take big risks in doing so. spending whole rounds in stance like KS requires opponents who are both impatient and have no idea how to counter it.
for example MST 6B is an option that leaves you with a lot of followups
if you just stop there and your opponent doesnt atack immediately, you can fish a CH with b6 or 3A for example
if your opp is trying to beat your 6~RLC, go for MST 6BB this is very risky (mst 6BB is very unsafe) but it just the way this game is. sometimes people may even miss a chance to punish (I wouldnt count on it) b/c they are intimidated. After MST 6~RLC there are a lot of options to go with. against overly agressive opponents RLC A interrupts nearly everything and will punish step, but I prefer backdash into RLC B it creates distance and creates very good situation on far block, making b6 a good CH fishing option. of course if its not far block you will get punished for RLC B, but RLC A is heavily punishable by most characters regardless of if you're going to shift into MST or not. Be extremely careful with RLC [A] near the edge, b/c some characters have TC back RO, that will punish you if you shift into MST. If your opponent is scared just enough or starts to step you (most people will step at a distance and just wait on close block) shift back into mst - most moves that counter relic transitions are high atacks, and shifting into mst solves both this and turtling problem. On wakeups RLC K and RLC A+B variations are a decent options, especially if you can guess correcty, at close range you can really poke with RLC K a lot even if your opp steps to the left or blocks you can still press on the advantage as RLC A+B+K or RLC A will beat out most of what they may try as a punishment. RLC A+B{1} (GB) is good against step and fast counters, RLC A+B{2} is good against anything else. the rest is highly situational.
However most of this is purely theoretical, in reality or in numbers RLC has direly high risk as opposed to reward so only way to make it favorable is to catch your opponents off guard, which is not, of course, going to happen if you use it a lot or in same situations. The risk of both stances depends on the characters you are fighting against. some characters can punish stance extrememly well, some can punish only one stance well, so you should keep an eye on this kind of things.
MST is generelly weak to SSR and TC moves, so if your opponents blocks transition move he will probably atack with something to beat this. check out what he does to counter transition and adapt accordingly. If you can go into mst in a broad daylight only do so at certain ranges, where you can reach opponent with mst throw. otherwise you'll get stepped and punished, also 6B+K transition is slow and can be interrupted with generic 2A if your opponents anticipate this. however if you can be unpredictable with MST your opponent wont be able to react in time and miss his opportunity to interrupt or step. so unpredictability is the key, too.
On wakeups. MST 6BB may hit both if your opponents sideroll incorrectly (left), to the right it will have no tracking at all, however on mid-far range mst K on grounded opp will hit all siderolls and give a large ground stun that allows uninterruptible 66A+B. the rest is up to you to guess what will opponent do. if he gets up just mix him up with MST 6B/MST KB, if he stays otg MST K into 66A+B_66A+B~G. use your imagination and try to be unpredictable with stance.
