I usually go for one water type for surf, one flying type for fly, and after that I usually wing it. Oftentimes I will have a fire-grass-water trio, but that's not always true.
can we all agree that the Bug type sucks? and to a lesser extent poison and ice?
No, we can't. Bug has always been a powerful asset when it comes to super effective, because of it's super-effective to Psychic and Dark, neither of which have many weaknesses. And maybe you might say Psychic isn't a threat anymore, but Dark types crawl every corner of Unova, so taking the bugs with you isn't that bad anymore. Sure, not many are that great, but Gen IV introduced several powerful ones as well as X-Scissor and Bug Buzz,and Gen V didn't give us single bug that
wasn't great, other than Leavany's (Sp?) horrible typing. It's actually only weak to three types, and 4X resists the common Fighting type frequently due to combining with Poison or Flying types.
Poison, typewise,
is awful. However, I have discovered that they are an extremely versatile type, especially in generations where the Nidos are available, not to mention that almost all can learn Giga Drain from TM before Gen V, and could therefore have been used as a defensively capable Grass type. They also have received better moves in recent generations, such as Gunk Shot (debatable as to whether it's better due it's accuracy) and Slime Wave/Sludge Wave/ whatever it is in English.
Ice is iffy. It's offensive power is matched only by Fighting, Rock, and Ground, and the types it's super-effective against are generally rather tough, and it is very commonly 4X super effective against Dragon. It's generally more beneficial to give Ice Beam or Blizzard to a non-Ice type Pokemon, though, because the only types
worse at defense are Grass and Rock.
In conclusion, no, these types are not worthless. My Accelgor kicked Ghetsis' Hydreigon's butt in two hits with a -Sp. Atk nature, because of Bug type's awesomeness. Sorry for the rant, but I felt I had to do this.
