Ashall-Bott, 23, was a free agent after finishing last season at Salford Red Devils under Watson.
Huddersfield have moved to snare him after first-choice No1 Ashton Golding dislocated his shoulder in pre-season training, ruling the former Leeds Rhinos player out until the end of May.
An elusive ball-carrier, Ashall-Bott had initially signed for Ottawa Aces in August in readiness for their inaugural campaign.
However, just three months later, the new Canadian franchise delayed their start in League One until 2022 in light of the ongoing uncertainty over travel restrictions due to Covid-19.
Ashall-Bott burst onto the scene with hometown Widnes Vikings in 2018, impressing in Super League with a number of eye-catching performances.
But a serious back injury the following year thwarted his progress and he joined London Broncos for 2020 only to see the Championship season ended in March due to the pandemic.
Watson took him to Salford in September, however, and the former England Youth international impressed in his three appearances for the Challenge Cup finalists.
Obviously, Great Britain assistant coach Watson switched to Huddersfield in the autumn and has been busily revamping the West Yorkshire club’s squad.
Their recruitment looked to be done but Golding’s injury has prompted this move for a player the Giants coach rates highly.
“Olly’s got so much potential and, over the last few years, you can see that,” Watson told The Yorkshire Post.
“He’s just had some really tough luck with injuries but he went to London and they really invested in his rehab’ programme.
“They got his back fixed and he had an op’ to get that sorted. He came to us at Salford last year and the rehab’ work has put him in a really good place physically.
“He just wasn’t’ match fit. But he showed potential, especially in the games against Hull KR and Warrington; he went really well.
“He came to Salford on trial and then we signed him for the rest of the year but he was available again now. With losing Ash, we obviously have people who can drop in at full-back. Will Pryce has been training there with us and Aidan McGowan.
“But having someone like Olly, who’s a genuine full-back, gives us a little bit of peace of mind that there’s someone there who’s got experience of playing at a good level in that position.”
Speaking about Ashall-Bott’s attributes, Watson said: “He is lightning; he’s unbelievably quick.
“We knew he was quick anyway but when we brought him in at Salford last year, the speed and way he moved around the field, he was cruising around the top of the ground. Firm tracks really suit him. Defensively, he’s well aware of that side of his game and, even though he’s only small, he does not mind putting his body in front of big lads.
“Full-backs are the boss of the ‘D’ line, so you have to have that mentality that you have to defend it first and he can do that.
“But his speed will get him out of trouble anyway and cause problems in attack.”
Watson could move regular winger Darnell McIntosh to the No1 role when the season begins on March 25 or even switch stand-off Lee Gaskell if needed.
However, the arrival of Ashall-Bott, who can also play on the wing, will certainly give Huddersfield that extra strength in depth.
Watson is confident the unfortunate Golding will overcome his latest setback.
The Jamaica international missed the start of the last campaign after suffering a major hamstring injury in pre-season after joining from Rhinos.
But Golding, 24, was excellent on his return, scoring twice in 11 games, and he will look to bounce back again especially with the World Cup at the end of the year.
Watson said: “He’ll be back.
“He was really into his pre-season and this has come as a blow and disappointment.
“But we’ve just said that he’s proved it over time; he’s come back from injury before and had a couple of bad bumps with pre-season now.
“But that’s part and parcel of rugby; taking adversity and coming through, The way he is as a pro’ he’ll be fine.”
Meanwhile, Watson added that regular hooker Adam O’Brien is shaping up well after fracturing a bone in his neck against Leeds in September.
The coach said: “He’s been training all the way through with us so he’s fully up and running.
“With Adam, James Cunningham, George Roby and young Kieran Rush in the academy who can compete for that spot, again, it’s good.
“Adam’s looking really good; he’s killing it with fitness.”
Giants have introduced academy products Pryce, Fenton Rogers, Connor Carr and George Collins to their first-team training recently before their facility was shut down on Thursday due to a Covid outbreak.
Support The Yorkshire Post and become a subscriber today. Your subscription will help us to continue to bring quality news to the people of Yorkshire. In return, you’ll see fewer ads on site, get free access to our app and receive exclusive membiers-only offers. Click HERE to subscribe.