blitzlefan
shake it off!
Although Forretress does discourage the usage of entry hazards while it's in play, it very rarely provides "pressure", seeing as it has rather mediocre offensive stats and is rarely used in an offensive manner. Also, Deoxys-S, Deoxys-A, Dialga, and Groudon all have moves commonly used to effectively beat Forretress, namely Fire Punch, Hidden Power Fire, Fire Blast, and Fire Punch/Fire Blast/Overheat, in that order.
I'm going to ignore the condescension and simply going to reply with usage statistics to solve this. Before you make claims like the one you made above, you should probably check the most recent usage statistics first.It forces your opponent to switch into their spin blocker aka applying pressure. But then again you don't understand the concept of defensive pressure. Those mons that you mentioned rarely run those moves and if they did a combination of sturdy + custap berry still allows the forry user to get ahead.
Groudon:
A good 40% of all Groudon have a Fire-type coverage move, and Fire Punch / Fire Blast is sun-boosted, meaning Groudon can beat Forretress a decent amount of the time.
| Earthquake 98.350%|
| Stealth Rock 63.780%|
| Stone Edge 53.548%|
| Thunder Wave 40.284%|
| Fire Punch 38.710%|
| Dragon Tail 34.735%|
| Rock Polish 12.904%|
| Dragon Claw 12.770%|
| Roar 11.818%|
| Swords Dance 10.941%|
| Fire Blast 3.567%|
| Other 18.592%|
| Stealth Rock 63.780%|
| Stone Edge 53.548%|
| Thunder Wave 40.284%|
| Fire Punch 38.710%|
| Dragon Tail 34.735%|
| Rock Polish 12.904%|
| Dragon Claw 12.770%|
| Roar 11.818%|
| Swords Dance 10.941%|
| Fire Blast 3.567%|
| Other 18.592%|
Deoxys-S:
Taunt, Magic Coat, Fire Punch, and HP Fire cripple Forretress and render it useless. Taunt / Magic Coat are run on the vast majority of Deoxys-S, and about a quarter of them have a Fire-type coverage move.
|Stealth Rock 92.637%|
| Spikes 83.459%|
| Taunt 67.707%|
| Magic Coat 29.884%|
| Fire Punch 23.000%|
| Psycho Boost 13.060%|
| Ice Beam 12.862%|
| ExtremeSpeed 11.923%|
| Light Screen 8.662%|
| Hidden Power Fire 8.293%|
| Superpower 7.862%|
| Reflect 7.845%|
| Shadow Ball 6.502%|
| Thunder Wave 4.139%|
| Trick 3.659%|
| Other 18.505%|
| Spikes 83.459%|
| Taunt 67.707%|
| Magic Coat 29.884%|
| Fire Punch 23.000%|
| Psycho Boost 13.060%|
| Ice Beam 12.862%|
| ExtremeSpeed 11.923%|
| Light Screen 8.662%|
| Hidden Power Fire 8.293%|
| Superpower 7.862%|
| Reflect 7.845%|
| Shadow Ball 6.502%|
| Thunder Wave 4.139%|
| Trick 3.659%|
| Other 18.505%|
Deoxys-A:
Admittedly, a fewer number of Deoxys-A have a Fire-type coverage move, but a fifth can reliably beat Forretress.
| ExtremeSpeed 70.211%|
| Psycho Boost 68.908%|
| Superpower 65.271%|
| Ice Beam 42.738%|
| Thunder 22.508%|
| Thunderbolt 19.157%|
| Fire Punch 17.433%|
| Shadow Ball 15.472%|
| Stealth Rock 13.641%|
| Hidden Power Fire 7.081%|
| Spikes 5.918%|
| Grass Knot 5.650%|
| Psychic 4.602%|
| Zen Headbutt 4.201%|
| Ice Punch 4.136%|
| Focus Blast 3.462%|
| Dark Pulse 3.212%|
| Low Kick 2.767%|
| Psyshock 2.545%|
| Taunt 2.541%|
| Other 18.545%|
| Psycho Boost 68.908%|
| Superpower 65.271%|
| Ice Beam 42.738%|
| Thunder 22.508%|
| Thunderbolt 19.157%|
| Fire Punch 17.433%|
| Shadow Ball 15.472%|
| Stealth Rock 13.641%|
| Hidden Power Fire 7.081%|
| Spikes 5.918%|
| Grass Knot 5.650%|
| Psychic 4.602%|
| Zen Headbutt 4.201%|
| Ice Punch 4.136%|
| Focus Blast 3.462%|
| Dark Pulse 3.212%|
| Low Kick 2.767%|
| Psyshock 2.545%|
| Taunt 2.541%|
| Other 18.545%|
Dialga:
Fire Blast is the most commonly used move on Dialga, and over half of all Dialgas haev a Fire-type coverage move.
| Fire Blast 54.014%|
| Draco Meteor 53.197%|
| Dragon Pulse 49.301%|
| Stealth Rock 48.707%|
| Thunder 40.219%|
| Aura Sphere 37.108%|
| Roar 21.977%|
| Dragon Tail 11.517%|
| Thunder Wave 11.102%|
| Thunderbolt 10.498%|
| Flamethrower 9.593%|
| Outrage 8.069%|
| Bulk Up 6.554%|
| Sleep Talk 5.530%|
| Ice Beam 4.920%|
| Rest 4.270%|
| Earth Power 3.506%|
| Other 19.917%|
| Draco Meteor 53.197%|
| Dragon Pulse 49.301%|
| Stealth Rock 48.707%|
| Thunder 40.219%|
| Aura Sphere 37.108%|
| Roar 21.977%|
| Dragon Tail 11.517%|
| Thunder Wave 11.102%|
| Thunderbolt 10.498%|
| Flamethrower 9.593%|
| Outrage 8.069%|
| Bulk Up 6.554%|
| Sleep Talk 5.530%|
| Ice Beam 4.920%|
| Rest 4.270%|
| Earth Power 3.506%|
| Other 19.917%|
Lastly, what exactly is defensive pressure? I've never heard of this term before now. Can somebody explain it to me please?
Edit: thanks