How do I beat the big monster?

You'd have to be a bit more specific, but if you're talking about the giant monsters often found at the end of levels, and usually jump and create shockwaves, you can either go into Unleash mode and attack it loads, or wait untill you've got the opportunity to perform a critical attack upon it, such as when the Quick Time Events occur.

If you mean the Werehog one,
jump over shockwaves, aswell as dodging the shockwave will kill most the bad guys. Keep attacking the big monster, and when a little arrow appears above his head (normally when his healthbar is low) press the B button and then press the buttons as they appear on screen to finish him off)

If you mean the one on the level that you meet tails,try using the unleash power,it makes you very powerful so you can beat him fast and clean,if you're having troubles with your health,or unleash gauge is not full,break some itens on the scenario

I wait to have helped

If you mean the one with the club kill all enemys first but if it does the shock wave it should take out most of em then go into unleased run to his back an slash away but run away before does the shockwave then jump over it rinse and repeat

method two: level up your combat till you get either the yyyyxxxx or xxxxyyyy then go into unleashed then spam those combos like a mo** after killing other enemys then just jump over his shockwave when he does it rinse, repeat

I am assuming that you are talking about a "boss" type monster. You best bet is to:

1. if you low on health, and you know their attack pattern, hit, run repeat.

2. Use Unleash, your attacks double along with speed etc.

3. Find any items that can help. Either heal, or attack boosters, anything that can help

4. You could try the shield, although i havent found the right way yet, as i keep getting hit anyway

What do you mean?

Do you mean the one with a titan and and a EXTREMELY small room? If so level up the life to max and when the titan jumps you jump too. While you're jumping attack. When you get unleashed mode use it imeadently and hammer down really long combos like yyxxyyxxyyxxyyxx. Repeat until it dies.

You mean the big mother on the spagonia level? If so then all you have to do is activate your unleashed and go all out on the big mother

If you mean Dark Gaia then I am having trouble too

Ya talkin' about those big ******' titans? Get into unleashed mode and rack up some combos. DO NOT guard when he jumps!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!