- Hackmons is a tier where you can have any ability, moves, EV spreads or your liking. Deoxys-S with Spore, and Blissey with Imposter are a few examples.
- Glitchmons is slightly different. You have only 508 EVs to spend, and you're stuck with your natural abilities. But the moves aren't exactly normal either. The only moves you can use are the moves the Pokemon learns naturally and those that can be obtained through glitches, such as the Mimic glitch.
A good rule of thumb to prevent this easy mistake is to look up what learns Mimic, Assist, Copycat, Metronome, and Transform in gens 3 and 4. Also note that unless the Pokemon learns it naturally, you can only have one gen 5 move due to needing Sketch for it. Gen 5 abilities are illegal with the mimic glitch as well. Finally, note that if a Pokemon from gen 3 doesn’t have a pre evo and needs mimic from the gen 3 tutor to do the glitch, then it won’t be able to have a gen 4 ability. For example, No Guard Machop with Sheer Cold and Scrappy Miltank with Rapid Spin are illegal, but No Guard Machoke with Sheer Cold and Skill Link Cloyster with Bone Rush are legal!