Rampardos is a god-tier design, a top-level bro, and based off the most patrician of dinosaurs, the Pachycephalosaurus.
I really want him to succeed, but unfortunately all he can do right now is niche trick room memes.
So, i propose that we...
>Give him Simple in his second ability slot.
>Give him Dragon Dance as an Egg Move
Simple is justified by his dex entries that state he has a small brain, e.g.

HG/SS/X/OR: Its skull withstands impacts of any magnitude. As a result, its brain never gets the chance to grow.
Sun: The result of repeated headbutts is a skull grown thick and hard. However, its brain has shrunk in size compared with Cranidos's.

With this, Rampardos would be either able to choose between a combined Swords Dance and Rock Polish in one turn (boosting a Jolly Rampardos up to an effective 858 Attack and 472 Speed).

What tier is it now? And how do we fix Bastiodon?
Bonus round: What tier would it be if you gave it Accelerock as an egg move as well? (yes i know that breaks my own rule of two)