these two seem like the type of champs you either barely lose to or lose very hard to you can't win lane unless their players don't have half a brain on them and the towers against them always fall fast because of being forced to recall constantly
Illaoi - Dodge E's and punish her when it's on CD.
Illaoi can be beat. Tryn can win if he plays nice to 6. Anyone rushing grievous wounds can beat Illaoi. Hard stun champs can beat Illaoi.
Most builds that insert armor can do well for awhile as well, because Illaoi takes a but to actually buy Black cleaver, and it's not always her first best item, and she rarely has budget to insert more Armor reducton/penetration than it.
Illaoi also has a really bad post lane. So many adcs and mages just destroy her with CC.
They have a few counters but you need to be the one picking into them. If they counter pick you then you won't have a fun time.
I've beaten Yasuo in the past as Poppy, Annie, and Veigar. Illaoi, however, I'm not too sure.
I usually wreck Yasuo from lvl 3 and after as 
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For vs. Illaoi just use a sustain lord who can cancel her ulti or get out of it to satety.
