Glitchmons is centered around the intricate Mimic glitch. Any Pokémon
that can learn the move Mimic, Copycat, Metronome, Transform, or
Assist in generation 4 has access to this glitch, which allows them to
learn any move in the game. This means that all generation 5 Pokémon
and Dream World abilities are illegal with this glitch. Pokémon may
also have one move of their choice from generation 5 if they are
transferred to BW with the move Sketch. Numerous Pokémon have access
to this glitch from the generation 3 tutors. Besides the Mimic glitch,
every Pokémon is legal in Glitchmons and all Clauses are off.
Hackmons is a bit different from the norm. You may use any Pokémon you
want, as well as any ability, 252 EVs in every stat, and any move you
want on said Pokémon. There are also no Clauses. This creates an
incredibly absurd metagame that has endless possibilities. Wonder
Guard is one of the most popular strategies to utilize, with Gastro
Acid, Mold Breaker, and various residual damage moves popping up to
counter it. Sorry to break the ice, but your Wondertomb is far from
invincible. There are so many possibilities that instead of trying to
counter every strategy out there, one should instead simply try to
successfully execute their own strategy. Every so often the ladder is
taken by storm by a new strategy... which is subsequently followed by
seemingly endless bitching. This happens in the standard metagames to
one degree as well, but it is not personified as much as it is here.
Creativity is the key to being successful in this metagame. - Smogon
Yeah, that's about it.