Actually, the reason why I want to play Random is for the achievement and portrait; archon. I don't really want to play for fun. Haha

I guess I will just go for mass speedlings and mass marines marauders in every single game, and hope for the best.

It really depends, Protoss will need to watch out if there is 2 Zergs in the opponent group, Zerg base usually gets targeted first due to their squishy nature.