Those guys were available as cereal premium with Kellogg's Frosties in 1996 in the UK.
Kellogg's Frosties box
front and
back, 1996 UK, Monster Sport Stars In My Pocket
Figures:
From the Kellogg's Frosties pack:
You'll have great fun with these sets
of "Monster Sport Stars"... the very
latest from the "Monster in my Pocket"
range.
Each set gives you four sporting characters
and 12 "super-stars" are exclusive to
Kellogg's, and are not available in the
shops!
All you have to do is to start collecting
this "deadly dozen" is save tokens from
special packers of FROSTIES. You'll find
4 tokens on the 1kg packs, 3 on the 750g
size, 2 on the 500g and 1 on the 375g size.
Each set of four is then yours FREE in
exchange for 8 tokens.
So start saving tokens now and send
them to the address shown, together
with 20p towards postage.
... one moster from Set A or Set B
can be found in special packets of 750g
and 1kg packets of Kellogg's Frosties.
Look out for the special packets.
Set A
A1
Slam Dunk 
A2
Full Back Drac
A3
Angry Oddity
A4
Scrundown
Set B
B1
Completely Batty 
B2
Spooky Sprinter
B3
Werewolf Slugger
B4
Tony The Referee
Set C
C1
The Big Dipper 
C2
Abominable Snowboarder
C3
Hard Puck
C4
Howlin One