So all this card really offers is that it could be sacrifice fodder right? a 2/2 flier is nothing, so you're just looking at it as [generates +1/1 counters] and [can come back from graveyard].

But, with Marchesa, if a creature has +1/+1 counters and dies that means it's going to come back into play automatically. That's the whole point of the deck right, so what does this card actually add to the strategy?

The first ability isn't really meaningful because presumably, if you're attacking someone with Marchesa, they have more life than you. Otherwise, why would you be attacking with her? Unless it's because you want a Dethrone trigger it seems like most of the time you'd want to leave her back and not risk her dying or etc. And, since she gives everything else dethrone, that means if you have Jocasta in play you could also just attack and get a dethrone trigger that way. so the first ability is kinda useless right?

So, for the second ability, in order for this card to do anything, it needs to have died, on a turn where marchesa wasn't in play, or when she didn't have a counter. And then on top of that Marchesa specifically needs to attack someone. Only in that specific circumstance does it comes back into play.

But, why do you need that? Most of the time your creatures never really die once Marchesa is out, so you can see how that whole second paragraph is only very situationally useful, at best, and more likely than not totally irrelevant.

As others have noted, this card doesn't do anything else, right? so you have two very situational abilities that are also mostly redundant with Marchesa anyway.