He kind of equalizes the whole cast meaning he can do the same basic combos with the right line up. Only thing that makes Olimar bad is his literally broken recovery.
He also kind of falls apart to spacies a little bit, but you can deal with those fairly well.
There is more than that. Here is some more details
Pros:
Good usmash that turns into combos or a free grab
Decent/good combos depending on pikmin line up
Decent throws
Tilts are good, but usmash beats utilt in most ways. Ftilt is an amazing edge guard move. Dtilt can setup after 42% for edge guards so, dtilt>fair>let it begin
Purple pikmin can gimp just by tossing them
Free follow up after Pikmin slide(SH side b waveland)
Pikmin slide can also be used to retreat
Doesn't demand a lot of tech skill
Good edge guard skill set
A projectile that can beat a lot of other projectiles
Decent DD it's wide but slow
He can mix up his recovery and drop from his down b just to do it again, so he has some options
Good recovery
Having people above you is the best place to be
Chain grab on certain characters
Flowered yellow has more hit stun
Flowered whites cause poison and how much depends on said moves (which is to dam ez to remove)
Flowered purples have the best KB
Flowered reds are a nerfed purple
Flowered blues are basically the normal pikmin
Cons:
Good weight to combo
Nothing to really save you from combos
Sub par normals
(Nvm)
Your pikmin take half a minute to flower and 15 sec to bud
When being knocked into a tumbling state, your pikmin tend to fall off and die
Pikmin die quickly
Your pikmin can be knocked into a blastzone/off screen and take a while to come back, even when you whistle
When you fsmash near the ledge you can't whistle that pikmin back
He can't deal with pressure well, especially against aggressive players or characters
You can't alter the arch at which you throw your pikmin at all
Your spike is so slow, you can't combo into and have to bait people for it to work(unless some flowered yellow atk works that I don't know about)
All in all, this is a low tier character you're walking into, you probably don't wanna pick this guy up, till he gets buffed. But if you like the character and his design, I ain't stoppin you.