DOOM V is great against Galactus ... but the problem is pulse wave. I thing that doesnot exists an effective way of beating Galactus ...

Yes, team of 30 Rookie Destinys could do it

Forget about Shazam and Magog on the first wave if dealing with 1800 point Galactus.

You need to perplex up a pulse waver or two and blast him off of that first dial. If Galactus stays on that first dial for more than a turn, it's over.

Your heavy hitters can attack on the second or third wave once Galactus has been knocked down to Invulnerable. This way the damage sticks without him being able to Impervious out of it.

A Veteran Doctor Fate or U Mordru are your friends.
They both require two hit from Big G (Even at the top of his dial) to KO. That is a guaranteed two clicks.

They are good for wildcarding and Fate can get you a PC roll provided you get into range.

Build your formation and rush him. Hope for the best.

With a baseball bat. Oh... Oh... and maybe some combat boots!