A single fleet should be mono-type. You don't get significant tactical advantages from having multiple types in a single fleet, but you suffer a real strategic disadvantage forcing your corvettes to fly around the galaxy at battleship speed when they could be moving twice as fast.
Late-game, grab one fleet of corvettes (mix of anti-shields and point defense). The high speed of the corvettes helps them pin enemy forces in place while you bring up the big guns, and their point defense and high evasion lets them tank early salvos without suffering the loss of expensive battleships. Then you get a pair of battleship fleets as your sledgehammer that follow in right behind, smash everything and mop up. After you've won the big battles you can divert your corvette to quickly mop up little stuff while the battleships grind through hard points.
Strike craft are awful. Don't get them. Point defense is situational; depends on what designs your enemy is throwing at you. Against AIs, I wouldn't worry about it in early/mid-game. In PvP there are some humans who are obsessed with missile/torpedo corvettes, and mixing in some PD will help against them.
Shields vs. armor, and shield damage vs armor damage vs bypass, is very enemy dependent. Need to look at what you're up against and also what tech you have available. A good general-purpose fleet for a variety of opponents has balance - even mix of shielding and armor, damage bonuses spread across all types.
Late-game, grab one fleet of corvettes (mix of anti-shields and point defense). The high speed of the corvettes helps them pin enemy forces in place while you bring up the big guns, and their point defense and high evasion lets them tank early salvos without suffering the loss of expensive battleships. Then you get a pair of battleship fleets as your sledgehammer that follow in right behind, smash everything and mop up. After you've won the big battles you can divert your corvette to quickly mop up little stuff while the battleships grind through hard points.
Strike craft are awful. Don't get them. Point defense is situational; depends on what designs your enemy is throwing at you. Against AIs, I wouldn't worry about it in early/mid-game. In PvP there are some humans who are obsessed with missile/torpedo corvettes, and mixing in some PD will help against them.
Shields vs. armor, and shield damage vs armor damage vs bypass, is very enemy dependent. Need to look at what you're up against and also what tech you have available. A good general-purpose fleet for a variety of opponents has balance - even mix of shielding and armor, damage bonuses spread across all types.