Have 2 monsters (+) and 2 other monsters (-) the synthesis each monster with each other.
You must scout it. You can't synthesize it!
Gigantes and Buffalaogre
you just synthesize 2 goodybags
You need to synthesize Rhapthorne 2 and Orgodemir into one monster, then synthesize Captain Crow and Gem Slime into another monster. When you synthesize the two newly synthesized monsters together, you get Dr. Snapped. If you need any more help, check out Gamefaqs.com
To synthesize Metal Liquid Slime in Dragon Quest Monsters: Joker, you'll need specific ingredients. Combine a Metal Slime with a Liquid Slime in the synthesis menu. The resulting Metal Liquid Slime will inherit attributes from both parent monsters. Ensure your monsters are at suitable levels to improve synthesis success.
to get a khalamari you need to synth a khalimari kid and a khalimari kid together and a king squid and a king squid together and then synth the two result monsters together to make a khalimari
synthesize dhoulmagus(alabast dragon + psaro) with nimzo(draculard +malroth)
First make an Archdemon (Dessert x Megaladon) Then synthesize him with mostly anything.
fuse a green dragon with a metal slime
You synthesise a Behemoth slime and a behemoth slime (found on the she slime and slime uncharted island) Or you can synthesize 4 slimes together.
Gigantes+Buffalogre I used them for ++ attack mine had 100 at lvl 1 =D
just get a dragon based monster and fuse it with other monsters but make sure you fuse them into dragon based monsters