The Suns entered Saturday's match featuring nine players who made their AFLW debuts last week, and their youthful exuberance proved hard to stop in the upset 10.9 (69) to 5.4 (34) win.
Welsh was the biggest star of the day, with the 18-year-old kicking 5.0 from 10 disposals in a dominant effort in attack.
"It's awesome," Welsh told Fox Footy after the match.
"But we just wanted the result at the end of the day. I'm super excited for the rest of the year. It shows the rest of the comp: look out, we're coming."
Charlie Rowbottom was a force in the midfield for the Suns with 26 disposals, six clearances and nine tackles, while second-gamer Ava Usher chipped in with two goals, including a three-bounce effort on the run.
For West Coast, former skipper Emma Swanson battled hard with 26 disposals and 471m gained, while star midfielder Ella Roberts racked up 24 possessions, seven clearances and 301m gained.
But the Eagles, finalists last year, are now 0-2 after starting the season with upset losses to GWS and Gold Coast.
Welsh was a star in the air and at ground level, with her neat dribble goal from the pocket in the second quarter showcasing her quality.
Over at Whitten Oval, Emma McDonald scored three first-half goals and Isabelle Pritchard starred through the midfield as the Western Bulldogs posted an 11-point win over Richmond.
The Dogs entered the match without star midfielder Ellie Blackburn due to a hamstring issue, and they were dealt another blow when midfielder Deanna Berry injured her collar bone after being crunched with a bump while kicking in the first quarter.
Berry was sent off to hospital for further assessment.
But McDonald's first-half burst and a career-high 36 disposals, nine clearances, nine tackles, one goal and 489m gained from Pritchard ensured the Bulldogs were able to secure the 7.6 (48) to 5.7 (37) win.
"It was a good game. We held on there. We were pretty cooked by the end, but it was good to get the win," Pritchard said after the Bulldogs went 2-0 to start the season.
"We had a big loss in Blackburn obviously, but we have enough depth that we can cover that hole that she leaves, which is massive."
Monique Conti stood tall for Richmond (1-1) with 26 disposals, six clearances and 669m gained, while No.1 draft pick Olivia Wolmarans showcased her potential with 3.0.
Wolmarans has been working closely with the Tigers' goalkicking coach Brendan Fevola since arriving at the club, and she showed off the good work by nailing a 40m set shot early in the match.
But Pritchard racked up 12 disposals and five clearances during the opening term to lay the foundations, with the Bulldogs able to hold Richmond at arm's length for the majority of the match.
