They could combine Types to allow Pokemon to technically become triple type Pokemon
Masquerain becomes Storm / Bug type however Pelipper remains as Water / Flying. The combined types would just be used to give Pokemon all the types they deserve
Storm Type (combination of Flying / Water) Weak (x2) Rock, Electric Resist (x0.5) Fire, Water, Fighting, Bug, Steel Immune (x0) Ground
Seismitoad could become Mud / Poison while Swampert and Quagsire could become pure Mud Type in order to give them more viability
Mud Type (Combination of Ground / Water) Weak (x2) Grass Resist (x0.5) Fire, Poison, Rock, Steel Immune (x0) Electric
(Combined types still retain the maximum weakness of x2 and resistance of x0.5 even if they should have a x4 weakness or a x0.25 resistance so that Pokemon that are pure combined types (Like Swampert in the above example) can fight on an even playing field. )
Ive thought for a while that a 'Rubber' type would work pretty well. It would need to be immune to Electric, resist Fighting Ground and Rock, but be weak to Fire and Steel.
Maybe they could also introduce triple types. For example, Gyrados can become Dragon-Water-Flying.
And then, everything currently with the Levitate ability can gain an extra 'Levitate' type which would be immune to Ground attacks, but weak to Flying. This would of course free up their ability slot for something more interesting.
Maybe they could add some kind of 'Mythical' or 'Legendary' type. Resist Fighting and Dark, but be weak to Poison. It would need to be retroactively added to some of the previous legendaries. --- No one, not even a demon, can deny a man his Pizza Shack Teriyaki Pizza.
I think if we're going to bother adding new types, they should help balance out the completely broken weaknesses, strengths and resistances. How about:
Super Effective against: Dragon, Curse Not Very Effective Against: Ice, Poison, Ghost Weak to: Curse, Poison Resists: Dragon, Fighting
Basically, the uber powerful dragons have something to keep them in check a little. Ice gains a much needed resistance. And Poison gets the super effective hit it desperately needs. --- "The most important thing is to never stop questioning." -Albert Einstein. Xbox Live: AlteraLateralus