Ratchet and Clank: Size Matters Tips
an easy way to defeat emperor otto on the first run through the game (ie. not challenge mode) is to get the electro rocket (v.4 of the shock rocket) with the lock on mod (quite cheap, only 5000 bolts from the mod vendors)thhe Laser Tracer v.3, the repulser field (or static barrier)the fully modded dual lacerators and the PDA.set your quick select up (through the weapons menu)so it has these weapons and some others of your choice in it. then load up on ammo and go challenge otto(hint: if youve already got up to the battle stage where he has that annoying shield, theres a teleport by your landing padto go fight him straight away). start by energising your Repulser field/static barrier and then shooting at him with your laser tracer. you do get hurt usually by one of his attacks doing this but it pays off, as it knocks his shield out within a couple of seconds. then, lock on to him with your electro rocketand hold down circle. strafe so he stays roughly in the centre of your screen or you risk losing your lock.when he gets his shield again, repeat process. keep going until you run out of ammo or he stops using his shield. now continue dodging his attacks while shooting him constantly withthe electro rocket and lacerators. should you run out of ammo, use the PDA (make sure you have lots of bolts beforehand though, as this can me quite costly) pretty soon you should have him dead and voila you have completed the game. Once. Then you have the option of either replaying the game in challenge mode (which i did) or time warping back to before you confronted otto. i have no idea what the latter option does, though. GOOD LUCK!