What type of cartridge should get for?

As some of you probably know I just bought a turntable, my problem I been out of this circuit for long time and when I was I used to use Audio Technicas AT-21, AT-15 and AT-13 if I remember right, I think that the AT-21 was Gold and the 13 was red. But I don’t remember why I pick them or even if I had a reason to pick them.
Well now that I bought a old turntable ( Optronica RP-3434) that I think originally come with a VM Cartridge that to be honest I do not have no clue what that means.
So the question is CAN I USED ANY TYPE OF CARTIDGE ON ANY TURNTABLE? Can I uses and MM or MC or MI ? Or what type of cartridge should I get for it?
If I could I would like to try a Grado MI... Can be done with this turntable?
Now if I can solve my first problem then the second show up..... What is the difference between Regular mount and P mount?
If I sound ignorant it’s probably because I’m on this matter, but with your help I’m planning to make the right decition.
Thank you
audio technica 150...mm
P mount is a plug in- fixed position female connectors on tone arm, male pins on cart (or other way around, no matter). A technology that never caught on much, no way to optomize azimuth or overhang, not very rigid connection to arm. YOu can use either an mm (or mi, pretty much same thing) or mc cart on any table, but you the phono stage will have to have sufficient gain if you use an mc cart, unless it is high output, or unless you insert a step up transformer or active pre-pre-amp aka head amp to get the cart output high enough for your mm phono stage.
Thank you
I'm using a Audio Research SP-9 preamplifier with a phone stage from the preamplifier, That will be enogh for an MM?
The SP9 has sufficient gain there should be a switch on the back for adjusting from low to high on the phono stage. I agree with the others you can definitely use any Cartridge you want the Grado Prestige series comes with a Flimsy P mount head shell screws and all. I am not sure if you want to really invest much with table and arm. A Denon DL103 is a giant Killer.