I'm not going to say whether Olimar will have a problem with swords or not in Ultimate or if reduced Pikmin health will hurt him in the long run, but I have something to say about
while all we seem to have gotten is a different grab that isn't even strictly better as far as I can tell
I'm confident in saying that a reworked grab is all that Olimar got in the transition to Ultimate is objectively wrong. There's a
pinned thread that I periodically update, which details everything that changed and things that have possibly changed. For a summary of that thread:
- Olimar's throws are better in terms of damage and KO potential.
He actually has kill throws that actually do their job. Forward throw's better KO potential means he now has a more viable DI mixup throw option at the ledge. Back throw may not be as good as the other two but it does a decent chunk of damage with 1 pikmin and probably the most damage out of a throw with 3. Down throw combos are not as reliable as it previously was but still definitely there. The increased endlag with more Pikmin and pivot grab in general sucks and will need to get used to, but the devs seem to want players to stray away from using grabs often in general, and Olimar has other important changes to his kit that his grab game has to get a nerf at some point.
- Aerials are disjointed. This is really big; it means that Olimar can go for juggles with up air after knocking the opponent up with down tilt, up tilt, or up smash. He can fight back if he's in disadvantage. He can go for down air spikes offstage and possibly still get a stage spike if he doesn't get the 1 frame sweetspot. Yellow pikmin have larger hitboxes than they did in 4, which goes hand in hand with disjointed aerials and allows Olimar to stuff certain aerials that he couldn't do otherwise. It overall adds his ability to push his advantage a lot more than what he could in 4.
- Frame 2-7 super armor and less endlag on whistle. Olimar still has to take the full brunt of damage, and it isn't reliable on certain multi-hit attacks, but having an option like this on a character well-known for their disadvantage state and in a game where you only have one airdodge is good and probably very important for Olimar players to get the timing down.
- Up smash's reduced endlag gives the move a lot more purpose in starting up juggles and as a good KO option to throw out, even if it's still a projectile.
- More damage on literally everything. Multiplier boosts on red and purple Pikmin mean that damage can add up really quickly on juggles. Damage increase for blue throws is always welcome, especially now that down throw combos are more situationally dependent. Latch damage from any of the three primary colors is now an actual threat if unattended, which (along with reduced HP) gives the opponent an incentive to try to kill them and more of a reason for the Olimar player to go in and punish.
- The universal run speed boost and jumpsquat frame reduction. Less frames to jump is probably why combos from down tilt and up tilt are more possible. The run speed may not seem important for someone like Olimar, but running smashes and a disjointed forward air are good if you have to get on the offensive. Also, the game is, as you said, more fast-paced than Smash 4, and there are going to be situations where sitting back and throwing stuff is not the best solution.
I don't think that I'll convince you that Olimar is in a better spot in this game, but as someone who has been recording these changes in a document for the pre-release months and someone who has done a lot of testing on this character before, I felt like I had to say something.