Yeah is it weird that after a while she works fine tho just runs like shit for first 20 mins
I can't comment too much on behavior. From my understanding, I can kinda see it running "alright". The temp from the combustion may burn off whatever is on the plug enough to get a good spark and, at the engine's high RPM, the moment of the crank shaft could possible be enough to keep the piston going with a weak spark. And being an inline engine, you really wouldn't notice changes in vibration at high RPMs.
But as
@JPass said, replace the spark plugs annually. I do that and they're really cheap. Got some cold tip iridium sparks, same size as the recommended one, hoping they'd be nicer than stock for like $2 more. I think i spent less than $20 for 8 spark plugs, which I then kept the extra 2 as spares. I can't really comment on how those spark plugs did since I had brought the boat in to get looked at and wanted them just to lubricate the jet pump assembly and boat, since I did the oil change and plugs already, but they didn't listen to me and replaced my brand new plugs with 3hrs on them with the stock ones. But for those 3 hours, ran great as far as I can tell!!
For annual service, definitely do a full oil change, oil filter, spark plugs, and if near 200hrs, pull the supercharger out to get rebuilt with the updated washer. Since you have the 255hp engine, also do the air filter. the 210 challenger, with twin 215hp engines don't have air filters for reasons I don't know, but the rest should be the same in regards to service. Lubricate the seals, jet pump assembly, and boot, as well. I honestly don't know how to do that or where to get the grease. I'm fine working on part of the engines, but I am not personally comfortable pulling the jet pump assembly out so I plan on letting the dealer do that. Supercharger, its a pain to pull out, for me at least for my first time. I had some guidance on that but overall wasn't too bad. Getting the tools for those special inverted Torx bolts, but Amazon does have it. Since you have a signal engine, don't imagine it being bad and don't have to deal with tight spaces of twin engines, but I know accessing the engine in a speedster 200 is PAINFUL but hopefully its manageable in your 150.
Sorry for the long post, hopefully that may help you on a few things. If you pull your boat out, I definitely like to check under the boat and check the visible parts of the impellers and wear rings.