I think Ogerpon's alright. Speed and offenses are fairly reasonable stat numbers for it, and it basically trades Tera's unpredictability for Power (which to be fair more than a few Pokemon use it for anyway) with the same-STAB boost always matching its mask. Growth and SD are pretty good boosting moves this gen with Sun doing alright or to work out of the weather instead, plus the masks let it work without fear of Knock Off as a trade off for the item slot.
Grass STAB it's left with options between Power Whip standard, Horn Leech for healing, Grassy Glide if you expect/use Terrain from Rillaboom, and Ivy Cudgel if not using a Mask for the crit chance. Taunt, Encore, Synthesis are always useful options to have on hand for set-up opportunity. Coverage is available by mask and the abilities are distinct enough to give it different playstyles even with its statline, and without having to use up Tera outright to take advantage of those aspects.
That said I think Ogerpon's best form is going to be its base Teal Mask, at least in Gen 9, for item access, because Spikes are still cancer and switching into them (much less Rocks with the Hearthflame Mask) is going to cut into its sweeping or defensive potential unless we get more removal. Teal just goes hard on the Grass moves to bolster damage with an item for utility to set-up or boost, and if you Terastalize it, Embody Aspect boosts the most important stat in Pokemon for the Teal Mask (Speed) like a pre-nerfed Intrepid Sword/Dauntless Shield did to their stats, which makes Tera'd Ogerpon an excellent revenge killer/cleaner since the STAB boost stack can compensate Grass's Mid coverage before any item consideration. Not to say the other forms won't have their place but this is the one I see getting the furthest, especially as long as Tera sticks around in OU.
I have no VGC expertise to evaluate if Ogerpon has viability there.