Glacius is a tough match up for real. If they have hail on their head you have to watch out for shatter and cold shoulder and at the same time find a gap to hit. Learn to advance avoiding the back jumps plus kicks they may throw (don’t Crouch! They are overhead and can confirm!) You can punish those with very well timed crouching HK or an eclipse. Or well you could block and depending on the distance you can run uppercut (back forward + HK) / or go back forward LK (to hit low while sliding) or dash to start your pressure close to him.
When close to Glacius watch out for: puddle punch and throws (it has great reach). You never know when they are going to throw the first one (you will have to check how they feel the pressure and are willing to get out of it) but you have to be patient. You can also dash through puddle punch if your timing is right (eg, after a hard knockdown they can wake up with puddle punch you are able to dash through it, however some Glacius are good enough to stay c.blocking and attemp c.lp at you, there you can start mind games with overheads or throws).
If you know the c.HP (the sweep) distance is a very good tool to get some pressure on them if they want to shatter close to you, you may be hit with hail but you will also knock them down in order to start your pressure.
Not that good Glacius players don’t use hail properly and will try to abuse back jumping, cold shoulder and puddle punch pretty much. Just watch out for shatter and check the gaps, remember the right distance you catch them with Shadow leaping Slash if they dare to summon hail or escape jumping back but still not hitting you when trying jump back MK. Be patient ,if you rush too much you will be in trouble.
If not try this: use Glacius against other Wulfs and see how they approach the match. At least try those basics things I said: back jumping with kicks, hails,cold shoulder, and puddle punch.
Glacius in instinct: Remember heavies break armour. Overpower (back + HP) is very good, same as crouching HK and HP to knock them down. If they teleport there’s a timing when you can grab them, but I wouldn’t try that. I prefer to block them and then punish. A Good Glay will use hail to cover them up, that’s a little harder to deal with but not impossible. Anyway, his instinct is good and strong enough vs Wulf, so try to stay away until is gone. Chasing an armoured Glacius is not that easy, so force them to go after you and make mistakes.
Gargos is similar in the way you have to work when his zoning you out. Another hard match up specially when minions are out (that’s the harder part). Try to get rid with the minions first, with Jabs. I prefer being close to Gargos than Glacius in the way he has no invencible reversal like Glacius heavy puddle punch. He has a movement that will punish you if you jump but you can meaty him to avoid this (same as Maya no Shadow dp).
PS: if you main Aria maybe you can use her in those match ups. Aria can zone pretty well too and her offense with the assist is something to be worried about too xD