Starting in the 250SX West category, Plessinger was able to finish in fifth place on his AMA Supercross Championship debut, a result he would repeat at the following round.

[2] The 2015 AMA National Motocross Championship would continue Plessinger's impressive debut professional season, placing consistently in the top-10 before getting his first overall podium with third at Washougal.

[3] The 2016 AMA Supercross Championship would see Plessinger move to the 250SX East class and eventually finish runner-up to champion Malcolm Stewart.

This would be backed up by his best motocross season yet, finishing fourth in the final 250 standings, picking up hid second overall win in Tennessee.

[6] Plessinger received his first call up to ride for his country at the 2018 Motocross des Nations, on home turf at Red Bud.

A wrist injury sustained training ahead of the outdoor season ruled him out for the entire 2020 AMA National Motocross Championship.

In a depleted field, Plessinger was able to pick up three overall podiums and following the end-of-season playoffs, finished fifth in the inaugural 2023 SuperMotocross World Championship.

He started with the number one plate due to the team being defending champions, and posted the best individual result of the weekend by placing fifth in Sunday's opening race.

Plessinger started off 2024 strong, with multiple top five finishes and taking his first 450 supercross win at the third round in San Diego.