Ratchet is very versatile with a well balance of close to mid range moves. Use forward square to juggle, with any of his triangle moves great for reaching and gaining ap. His level 1 is diabolical, but be careful because he can be knocked out of it. In free for all, try catching the other three off guard and get them by surprise. Even better if they are near a wall. His level two is also good, as while its possible to not get kills with his level 1 you will at least get two with clank.
Raiden: NRAGH why is I no loved? Big Boss: You need to find a more political solution...tasty.
I play Ratchet all the time! He is my favorite and best character because I don't have as much fun playing the others in the cast. I know his moves very well and I win about 85% of my matches. I still feel I can get even better with him though.
I'll tell you all that I know, hope this helps. His neutral square wrench attack combos into lvl 1 when near an edge or wall. After you hit the opponent quickly follow and use your lvl 1 for an instant kill. (Always make sure there isn't an enemy behind you or you might die or waste your lvl 1.
Up square is my combo starter, hit it on the ground then use it again in the air, then use up triangle. Hold X to hover, (use this to follow the enemy you hit with up triangle.) You can follow up with circle in the air, then aim and shoot. If your opponent bounces off the wall following the up triangle, turn the other direction and use up triangle.
Forward square is a good juggler like the other guy stated. Use this move before the up square combo I stated above.
Down square is great if it hits because it gives you a free grab.
Triangle is quick when uncharged but it gives you space and meter when charged. Plus it destroys any traps or guards Sly or Sack Boy might have in store for you. It blasts through everything but E. Cole and Big Daddy, or Sack Boy's invincibility moves.
Side triangle, a good mid range move to build meter. If you hit and bounce them off the wall, then you can use the up square combo to follow it up.
Down triangle is great when used in the air, it gives you a brief stun on enemies to which you can move in and start a combo of your own. It's a great way to help your teammate when they have a level 3 or 2 active and the enemy is running away.
Up triangle is a good thing to spam to build meter fast and punish anyone standing on a platform above you.
Circle is great for long range, especially when jumping to snipe from above or below. It's great to use after using neutral square on your opponent.
Side circle is another good move to use after a neutral square attack. Send out the minions then aim your riffle and shoot them twice and then minions hit them while you make a new batch and repeat. It's also good way to make your opponent jump in the air.
Down Circle, the wall. I use it rarely but I need to more. I use it in the air to control space while fighting, or to get another hit on someone trying to fall out of my air combo. Typically it's used as a shield. It's good to use when you snipe a counter happy sly, if they counter they will get shocked by the wall your standing in. Also great to use in the AP Ball on the tower level.
Zircon is up circle, be careful, though he gives you some meter, he can be a liability because if he is hit, your opponent gets meter. I rarely use him.
Grab and shoot forward towards the wall or edge and use your lvl 1 for a kill.
Grab and shoot up followed by up triangle.
Grab and shoot down when near a hole and then kill the stunned enemy at the spawn point. Also use down to try to grab again, or when againist the wall to kill with lvl 1 while shooting outwards to cover yourself.
When someone is in your grab machine, you are invincible! But can still die from supers.
lvl 2 Clank, he is best used when an opponent is near you. Use circle to throw "slow down" bubbles and use X to hover as you desend. Once you have level 2, snipe and force the enemy to come to you. Becareful, Clank can die from other supers so be aware of what the enemy has before you use him.
lvl 3 Space ship. Depending on lag this thing can give you 5 kills or none at all. Press circle to shoot rockets. Have the aiming cursor slightly ahead of your target. If players are roll dodging then shot where they rolling and stand up. If lag is bad then go for Clank instead.
Ratchet is good in all 4 phases! 1v1, 2v2, FFA, and 2v1!