How do you 100% the original games?

[DANMATUS]

Hey,

I have the original discs for:

MGS1
MSG2: Substance
MGS3: Subsistence
MGS4

and I was wondering since there wasn't a trophy system for PS2, what counts as 100%ing these games?

Is it all about reaching the highest rank and completing the VR missions when it comes to MGS2:Substance or what does the community see as clearing and completing the classics?
While for MSG1 and MGS3 its just reaching the highest rank?

MGS4 is the easiest one since it actually has the trophies for it. I know I could go out and buy one of the collections and follow the trophies but I'm really enjoying the nostalga trip with playing the games on their said system.

Cheers!